Diabetic Neuropathy 

Updated: Jul 23, 2019
Author: Dianna Quan, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP 

Overview

Practice Essentials

Diabetic neuropathy is the most common complication of diabetes mellitus (DM), affecting as many as 50% of patients with type 1 and type 2 DM. Diabetic peripheral neuropathy involves the presence of symptoms or signs of peripheral nerve dysfunction in people with diabetes after other possible causes have been excluded.[1]

Signs and symptoms

In type 1 DM, distal polyneuropathy typically becomes symptomatic after many years of chronic prolonged hyperglycemia, whereas in type 2, it may be apparent after only a few years of known poor glycemic control or even at diagnosis. Symptoms include the following:

  • Sensory – Negative or positive, diffuse or focal; usually insidious in onset and showing a stocking-and-glove distribution in the distal extremities

  • Motor – Distal, proximal, or more focal weakness, sometimes occurring along with sensory neuropathy (sensorimotor neuropathy)

  • Autonomic – Neuropathy that may involve the cardiovascular, gastrointestinal, and genitourinary systems and the sweat glands

Physical examination should include the following assessments:

  • Peripheral neuropathy testing – Gross light touch and pinprick sensation; vibratory sense; deep tendon reflexes; strength testing and muscle atrophy; dorsal pedal and posterior tibial pulses; skin assessment; Tinel testing; cranial nerve testing

  • Autonomic neuropathy testing – Objective evaluation of cardiovagal, adrenergic, and sudomotor function in a specialized autonomic laboratory; may be preceded by bedside screening to assess supine and upright blood pressure and heart rate, with measurement of sinus arrhythmia ratio

Two classification systems for diabetic neuropathy are the Thomas system and the symmetrical-versus-asymmetrical system. The Thomas system (modified) is as follows:

  • Hyperglycemic neuropathy

  • Generalized symmetrical polyneuropathies

  • Sensory neuropathy

  • Sensorimotor neuropathy

  • Autonomic neuropathy

  • Focal and multifocal neuropathies

  • Superimposed chronic inflammatory demyelinating polyneuropathy

Distal symmetrical sensorimotor polyneuropathy is commonly defined according to the following 3 key criteria:

  • The patient must have diabetes mellitus consistent with a widely accepted definition

  • Severity of polyneuropathy should be commensurate with duration and severity of diabetes

  • Other causes of sensorimotor polyneuropathy must be excluded

Pure autonomic diabetic neuropathy is rare.

Asymmetrical neuropathies include the following:

  • Median neuropathy of the wrist (carpal tunnel syndrome)

  • Other single or multiple limb mononeuropathies

  • Thoracic radiculoneuropathy

  • Lumbosacral radiculoplexus neuropathy

  • Cervical radiculoplexus neuropathy

Diabetic polyneuropathy is commonly staged as follows:

  • NO - No neuropathy

  • N1a - Signs but no symptoms of neuropathy

  • N2a - Symptomatic mild diabetic polyneuropathy; sensory, motor, or autonomic symptoms; patient is able to heel-walk

  • N2b - Severe symptomatic diabetic polyneuropathy; patient is unable to heel-walk)

  • N3 - Disabling diabetic polyneuropathy

See Clinical Presentation for more detail.

Diagnosis

Laboratory tests that may be helpful include the following:

  • Fasting plasma glucose

  • Hemoglobin A1c

  • Complete blood count

  • Complete metabolic panel (electrolytes and liver function panel)

  • Vitamin B-12 and folate levels

  • Thyroid function tests

  • Erythrocyte sedimentation rate

  • C-reactive protein

  • Serum protein electrophoresis with immunofixation electrophoresis

  • Antinuclear antibody

  • Anti-SSA and SSB antibodies

  • Rheumatoid factor

  • Paraneoplastic antibodies

  • Rapid plasma reagin

  • Genetic screens

  • Hematology screen (for anemia)

  • Sequential multiple analysis-7 (renal function and electrolyte imbalances)/complete metabolic panel (CMP)

Other diagnostic modalities that may be considered are as follows:

  • Electromyography and nerve conduction velocity testing

  • Electrophysiologic studies

  • Magnetic resonance imaging

  • Computed tomography (including single-photon emission computed tomography)

  • Nuclear imaging

  • Doppler imaging

  • Microdialysis

  • Electrocardiography

  • Nerve and skin biopsy (now rarely recommended for clinical purposes)

See Workup for more detail.

Management

Key components of the management of diabetic neuropathy include the following:

  • Foot care, including regular follow-up, patient education, and referral as appropriate

  • Tight, stable glycemic control (most important for slowing progression of neuropathy)

  • Pain management (eg, with pregabalin, gabapentin, sodium valproate, dextromethorphan, morphine sulfate, tramadol, oxycodone, duloxetine, topical capsaicin, transdermal lidocaine)

  • Treatment of diabetic gastroparesis (eg, with erythromycin, cisapride [not available in the United States], metoclopramide, polyethylene glycol 3350, tegaserod [currently available only on an emergency basis])

  • Experimental therapies include aldose reductase inhibitors, alpha-lipoic acid, actovegin, and spinal cord stimulators.

Treatment of autonomic dysfunction must address the following:

  • Erectile dysfunction

  • Orthostatic hypotension

  • Gustatory sweating

Surgical treatment may be considered as follows:

  • Aggressive debridement or amputation for recalcitrant foot necrosis or infection

  • Jejunostomy for intractable gastroparesis

  • Implantation of a penile prosthesis for ongoing impotence

  • Bracing, special boots, or, in some cases, surgery for Charcot foot

  • Pancreatic transplantation for diabetes with end-stage renal disease

See Treatment and Medication for more detail.

Background

Neuropathies are characterized by a progressive loss of nerve fiber function. A widely accepted definition of diabetic peripheral neuropathy is "the presence of symptoms and/or signs of peripheral nerve dysfunction in people with diabetes after exclusion of other causes."[2, 3]

Neuropathies are the most common complication of diabetes mellitus (DM), affecting up to 50% of patients with type 1 and type 2 DM. In type 1 diabetes mellitus, distal polyneuropathy typically becomes symptomatic after many years of chronic prolonged hyperglycemia. Conversely, patients with type 2 diabetes mellitus may present with distal polyneuropathy after only a few years of known poor glycemic control; sometimes, these patients already have neuropathy at the time of diagnosis. (See Clinical Presentation.)

Neuropathies severely decrease patients' quality of life (QOL). Furthermore, while the primary symptoms of neuropathy can be highly unpleasant, the secondary complications (eg, falls, foot ulcers, cardiac arrhythmias, and ileus) are even more serious and can lead to fractures, amputations, and even death in patients with DM.

Since diabetic neuropathy can manifest with a wide variety of sensory, motor, and autonomic symptoms, a structured list of symptoms can be used to help screen all diabetic patients for possible neuropathy (see History). Physical examination of patients with suspected distal sensory motor or focal (ie, entrapment or noncompressive) neuropathies should include assessments for both peripheral and autonomic neuropathy (see Physical Examination).

Multiple consensus panels recommend the inclusion of electrophysiologic testing in the evaluation of diabetic neuropathy. An appropriate array of electrodiagnostic tests includes both nerve conduction testing and needle EMG of the most distal muscles usually affected. (See Workup.)

Management of diabetic neuropathy should begin at the initial diagnosis of diabetes. The primary care physician needs to be alert for the development of neuropathy—or even its presence at the time of initial diabetes diagnosis—because failure to diagnose diabetic polyneuropathy can lead to serious consequences, including disability and amputation. In addition, the primary care physician is responsible for educating patients about the acute and chronic complications of diabetes (see Patient Education). Patients with diabetic peripheral neuropathy require more frequent follow-up, with particular attention to foot inspection to reinforce the need for regular self-care. (See Treatment Strategies and Management.)

Management of diabetic neuropathy includes 2 approaches: therapies for symptomatic relief and those that may slow the progression of neuropathy. Of all treatments, tight and stable glycemic control is probably the most important for slowing the progression of neuropathy. Many medications are available for the treatment of diabetic neuropathic pain, although most of them are not specifically approved by the United States Food and Drug Administration for this use. Nonpharmacologic treatment includes rehabilitation, which may comprise physical, occupational, speech, and recreational therapy. (See Medication.)

Anatomy

A review of the anatomy of the peripheral nervous system can facilitate understanding of the classification of diabetic peripheral neuropathy. Peripheral neurons can be categorized broadly as motor, sensory, or autonomic.

Motor neurons originate in the central nervous system (CNS) and extend to the anterior horn of the spinal cord. From the anterior horn, they exit the spinal cord (via ventral roots) and combine with other fibers in the brachial or lumbar plexuses and innervate their target organs through peripheral nerves.

Sensory neurons originate at the dorsal root ganglia (which lie outside the spinal cord) and follow a similar course with motor neurons. Sensory neurons are subdivided into categories according to the sensory modality they convey (see the Table below).

Autonomic neurons consist of sympathetic and parasympathetic types. In the periphery, preganglionic fibers leave the CNS and synapse on postganglionic neurons in the sympathetic chain or in sympathetic ganglia.

The smaller fibers are affected first in DM. With continued exposure to hyperglycemia, the larger fibers become affected. Fibers of different size mediate different types of sensation, as shown in the table below.

Table. Subdivisions of Sensory Neurons (Open Table in a new window)

Fiber Type

Size

Modality

Myelination

A-alpha (I)

13-20 micrometers

Limb proprioception

Yes

A-beta (II)

6-12 micrometers

Limb proprioception, vibration, pressure

Yes

A-delta (III)

1-5 micrometers

Mechanical sharp pain

Yes

C (IV)

0.2-1.5 micrometers

Thermal pain, mechanical burning pain

No

Pathophysiology

The factors leading to the development of diabetic neuropathy are not understood completely, and multiple hypotheses have been advanced.[4, 5, 6, 7, 8, 9, 10, 11, 12, 13] It is generally accepted to be a multifactorial process. Development of symptoms depends on many factors, such as total hyperglycemic exposure and other risk factors such as elevated lipids, blood pressure, smoking, increased height, and high exposure to other potentially neurotoxic agents such as ethanol. Genetic factors may also play a role.[14] Important contributing biochemical mechanisms in the development of the more common symmetrical forms of diabetic polyneuropathy likely include the polyol pathway, advanced glycation end products, and oxidative stress.

For more information, see Type 2 Diabetes and TCF7L2.

Polyol pathway

Hyperglycemia causes increased levels of intracellular glucose in nerves, leading to saturation of the normal glycolytic pathway. Extra glucose is shunted into the polyol pathway and converted to sorbitol and fructose by the enzymes aldose reductase and sorbitol dehydrogenase.[15] Accumulation of sorbitol and fructose lead to reduced nerve myoinositol, decreased membrane Na+/K+ -ATPase activity, impaired axonal transport, and structural breakdown of nerves, causing abnormal action potential propagation. This is the rationale for the use of aldose reductase inhibitors to improve nerve conduction.[16]

Advanced glycation end products

The nonenzymatic reaction of excess glucose with proteins, nucleotides, and lipids results in advanced glycation end products (AGEs) that may have a role in disrupting neuronal integrity and repair mechanisms through interference with nerve cell metabolism and axonal transport.[17]

Oxidative stress

The increased production of free radicals in diabetes may be detrimental via several mechanisms that are not fully understood. These include direct damage to blood vessels leading to nerve ischemia and facilitation of AGE reactions. Despite the incomplete understanding of these processes, use of the antioxidant alpha-lipoic acid may hold promise for improving neuropathic symptoms.[18, 19, 20]

Related contributing factors

Problems that are a consequence of or co-contributors to these disturbed biochemical processes include altered gene expression with altered cellular phenotypes, changes in cell physiology relating to endoskeletal structure or cellular transport, reduction in neurotrophins, and nerve ischemia.[21] Clinical trials of the best-studied neurotrophin, human recombinant nerve growth factor, were disappointing. With future refinements, however, pharmacologic intervention targeting one or more of these mechanisms may prove successful.

In the case of focal or asymmetrical diabetic neuropathy syndromes, vascular injury or autoimmunity may play more important roles.[22]

Etiology

Risk factors that are associated with more severe symptoms include the following[23] :

  • Poor glycemic control

  • Advanced age

  • Hypertension

  • Long duration of DM

  • Dyslipidemia

  • Smoking

  • Heavy alcohol intake

  • HLA-DR3/4 phenotype

  • Tall height

Development of symptoms depends on many factors, such as total hyperglycemic exposure and other risk factors such as elevated lipids, blood pressure, smoking, increased height, and high exposure to other potentially neurotoxic agents such as ethanol. Genetic factors may also play a role.[14]

Peripheral neuropathies have been described in patients with primary DM (types 1 and 2) and in those with secondary diabetes of diverse causes, suggesting a common etiologic mechanism based on chronic hyperglycemia. The contribution of hyperglycemia has received strong support from the Diabetes Control and Complications Trial (DCCT).[24]

An association between impaired glucose tolerance and peripheral neuropathy has been construed as further evidence of a dose-dependent effect of hyperglycemia on nerves, although this relationship remains an area of some controversy for type 2 diabetes and prediabetes.[25, 26, 27, 28]

A study by Jende et al indicated that in patients with type 1 diabetes, the predominant nerve lesions of distal symmetrical diabetic neuropathy develop in relation to poor glycemic control and nerve conduction loss, while in type 2 diabetes, these lesions arise in association with lipid metabolism changes.[29]

A study by Pai et al indicated that in adults with type 2 diabetes, an association exists between variability in fasting plasma glucose and the risk for painful diabetic peripheral neuropathy. Using the coefficient of variation (CV) for fasting plasma glucose, the investigators found that, after consideration of HbA1c, the odds ratios for the development of painful diabetic peripheral neuropathy were 4.08 and 5.49 for the third and fourth CV quartiles, respectively, compared with the first quartile.[30]

A study by Altaf et al indicated that obstructive sleep apnea (OSA) is linked to small-fiber neuropathy in type 2 diabetes, with poly–adenosine diphosphate ribose polymerase activation being a possible mechanism behind OSA’s association with diabetic peripheral neuropathy and endothelial dysfunction.[31]

A study by Dabelea et al found that among teenagers and young adults who had been diagnosed with type 1 or type 2 diabetes during childhood or adolescence, the age-adjusted prevalence of peripheral neuropathy was greater in those with type 2 diabetes than in patients with type 1 diabetes (17.7% vs 8.5%, respectively). After modifications had been made for established risk factors measured over time, the odds ratio for peripheral neuropathy in patients with type 2 diabetes versus those with type 1 was 2.52.[32]

Epidemiology

United States statistics

A large American study estimated that 47% of patients with diabetes have some peripheral neuropathy.[33] Neuropathy is estimated to be present in 7.5% of patients at the time of diabetes diagnosis. More than half of cases are distal symmetric polyneuropathy. Focal syndromes such as carpal tunnel syndrome (14-30%),[34, 35, 36] radiculopathies/plexopathies, and cranial neuropathies account for the rest. Solid prevalence data for the latter 2 less-common syndromes is lacking.

The wide variability in symmetric diabetic polyneuropathy prevalence data is due to lack of consistent criteria for diagnosis, variable methods of selecting patients for study, and differing assessment techniques. In addition, because many patients with diabetic polyneuropathy are initially asymptomatic, detection is extremely dependent on careful neurologic examination by the primary care clinician. The use of additional diagnostic techniques, such as autonomic or quantitative sensory testing, might result in a higher recorded prevalence.[37, 38]

International statistics

In a cohort of 4400 Belgian patients, Pirart et al found that 7.5% of patients already had neuropathy when diagnosed with diabetes.[39] After 25 years, the number with neuropathy rose to 45%. In the United Kingdom, the prevalence of diabetic neuropathy among the hospital clinic population was noted to be around 29%.[40]  A study by Pan et al found that in Beijing, peripheral neuropathy had prevalence rates of 21.92% and 35.34% in patients with type 1 and type 2 diabetes, respectively.[41]

Diabetic neuropathy in racial minorities

No definite racial predilection has been demonstrated for diabetic neuropathy. However, members of minority groups (eg, Hispanics, African Americans) have more secondary complications from diabetic neuropathy, such as lower-extremity amputations, than whites.[23] They also have more hospitalizations for neuropathic complications.

Sex differences in diabetic neuropathy

DM affects men and women with equal frequency. However, male patients with type 2 diabetes may develop diabetic polyneuropathy earlier than female patients,[42] and neuropathic pain causes more morbidity in females than in males.

Diabetic neuropathy and advancing age

Diabetic neuropathy can occur at any age but is more common with increasing age and severity and duration of diabetes.

Prognosis

Patients with untreated or inadequately treated diabetes have higher morbidity and complication rates related to neuropathy than patients with tightly controlled diabetes. Repetitive trauma to affected areas may cause skin breakdown, progressive ulceration, and infection. Amputations and death may result.

Treating diabetic neuropathy is a difficult task for the physician and patient. Most of the medicines mentioned in the Medication section do not lead to complete symptom relief. Clinical trials are under way to help find new ways to treat symptoms and delay disease progression.

Mortality is higher in people with cardiovascular autonomic neuropathy (CAN). The overall mortality rate over periods up to 10 years was 27% in patients with DM and CAN detected, compared with a 5% mortality rate in those without evidence of CAN. Morbidity results from foot ulceration and lower-extremity amputation. These 2 complications are the most common causes of hospitalization among people with DM in Western countries. Severe pain, dizziness, diarrhea, and impotence are common symptoms that decrease the QOL of a patient with DM. In patients with diabetic peripheral neuropathy, the prognosis is good, but the patient's QOL is reduced.

In a Canadian study of patients with painful diabetic neuropathy being managed in a tertiary care setting, Mai et al found that at 12-month follow-up, significant improvement in pain and function had been achieved in almost one third of these individuals. That included pain reduction of 30% or greater in 37.2% of patients, functional improvement (reduction of 1 or greater on the Pain Interference Scale) in 51.2% of patients, and achievement of both of these measures in 30.2% of patients. Polypharmacy was found to be essential to symptom management and included the use of analgesic antidepressants and anticonvulsants.[43]

For more information, go to Diabetic Foot.

for more information, go to Diabetic Foot Infections.

Patient Education

Controlling diet and nutrition are paramount to improving the secondary complications of diabetes, including neuropathy. Patients with diabetic neuropathy should work with nutritionists or their primary care physicians to develop a realistic diet for lowering blood glucose and minimizing large fluctuations in blood glucose.

Patients with diabetic neuropathy should be encouraged to remain as active as possible. However, those with significant sensory loss or autonomic dysfunction should be cautioned about exercising in extreme weather conditions, which may result in injury. For example, patients with extremity numbness may not be aware of frostbite injuries during prolonged cold exposure, or those with abnormal sweating may become easily overheated in hot conditions. In most cases, consultation with the patient's regular physician is reasonable before the initiation of a regular exercise program.

Patients with diabetic neuropathy need to be educated on all aspects of their condition, and they need to know that it is very much affected by poor glycemic control. Prevention of diabetic neuropathy is potentially best achieved by having near-euglycemic control from the onset of DM. Even in patients with symptoms of diabetic neuropathy, controlling blood glucose to euglycemic levels reduces pain significantly. When a person has poor control and becomes euglycemic quickly, pain may be exacerbated (possibly due to an insulin effect), but this pain disappears in a few days. The bottom line for patients is that medications are imperfect. Many result in no pain relief for certain patients. However, glucose control is something that the patient can achieve that may reduce pain.

The importance of protection and care of insensitive feet cannot be overemphasized. Patients should be instructed to trim their toenails with great care and to be fastidious about foot hygiene. Any fungal or bacterial infection mandates prompt medical attention. The need for well-fitting shoes should be stressed.

Diabetic polyneuropathy is often associated with diabetic retinopathy and nephropathy. Patients with neuropathy should be counseled to seek appropriate eye care and discuss renal care and follow-up with their primary care physicians or endocrinologists.

Patient education should begin in the primary care office. The following outline reviews some common questions and answers that can serve as a springboard for discussion.

What is diabetic neuropathy?

Diabetic neuropathy is nerve damage caused by diabetes. In the United States, diabetes is one of the most common causes of nerve damage, also known as peripheral neuropathy. Diabetic neuropathy can affect nerves that supply feeling and movement in the arms and legs. It can also affect the nerves that regulate unconscious vital functions such as heart rate and digestion.

How does diabetic neuropathy occur?

Doctors have been studying this problem for many years, but they do not yet understand exactly how diabetes damages nerves. However, they have observed that good control of blood sugar levels helps prevent diabetic neuropathy and slows its progression, especially in patients with type 1 diabetes.

What are the symptoms?

Symptoms of diabetic neuropathy may include the following:

  • Numbness or loss of feeling (usually in the feet and legs first, then the hands)

  • Pain

  • Muscle weakness

  • Low blood pressure and dizziness when rising quickly from sitting or lying down

  • Rapid or irregular heartbeats

  • Trouble having an erection

  • Nausea or vomiting

  • Difficulty swallowing

  • Constipation or diarrhea

Pain from diabetic neuropathy may range from minor discomfort or tingling in toes to severe pain. Pain may be sharp or lightning-like, deep and aching, or burning. Extreme sensitivity to the slightest touch can also occur (allodynia).

A study by D’Amato et al indicated that among diabetes-related complications and comorbidities, painful diabetic polyneuropathy is the greatest determinant of depression in patients with diabetes. The study involved 181 patients, including 25 with painful diabetic polyneuropathy and 46 with the painless form of the condition.[44]

How can I help prevent diabetic neuropathy?

The following steps may help to prevent or slow the worsening of diabetic neuropathy[45] :

  • Control diabetes; try to keep blood sugar at a normal level

  • Maintain normal blood pressure

  • Exercise regularly, according to the healthcare provider's recommendation

  • Stop smoking

  • Limit the amount of alcohol intake because excessive alcohol also can cause neuropathy or make it worse

  • Eat a healthy diet and avoid elevated levels of triglycerides in the blood

  • Maintain a healthy weight

  • Keep follow-up appointments with the healthcare provider

How is diabetic neuropathy treated?

No treatment is currently available to reverse neuropathy. The best approach is to control the diabetes and other risk factors.

Muscle weakness is treated with support, such as braces. Physical therapy and regular exercise may help patients maintain the muscle strength they have.

Pain medications may help make pain more tolerable. Medications can be used to treat nausea, vomiting, and diarrhea.

Men who have trouble having erections because of neuropathy should talk to their healthcare providers. Medications can help a man achieve and maintain an erection, or prosthetic devices can be put in the penis.

Preventing injuries such as burns, cuts, or broken bones is especially important, because patients with neuropathy have more complications from simple injuries and may not heal as quickly as healthy individuals.

How can I take care of myself?

Diabetes patients can take the following self-care measures:

  • Work with primary care physicians and endocrinologists to control glucose levels

  • Examine the skin of feet and lower legs regularly to look for injuries

  • See a healthcare provider promptly for calluses, sores on the skin, or other potential problems so they can be treated properly.

  • Wear good-fitting, comfortable shoes that protect the feet

How long will the problem last?

Once a person has neuropathy, the symptoms will persist indefinitely, but most people with diabetic neuropathy are able to lead active, fulfilling lives. Keeping blood sugar under good control may stop neuropathy from worsening.

For excellent patient education resources, visit eMedicineHealth's Diabetes Center and Men's Health Center. Also, see eMedicineHealth's patient education articles, Diabetes Mellitus and Diabetic Foot Care.

 

Presentation

History

In type 1 diabetes mellitus, distal polyneuropathy typically becomes symptomatic after many years of chronic prolonged hyperglycemia. Conversely, patients with type 2 diabetes mellitus may present with distal polyneuropathy after only a few years of known poor glycemic control; sometimes, these patients already have neuropathy at the time of diagnosis.

Since diabetic neuropathy can manifest as a wide variety of sensory, motor, and autonomic symptoms, a structured list of symptoms can be used to help screen all diabetic patients for possible neuropathy.

Sensory symptoms

Sensory neuropathy usually is insidious in onset and shows a stocking-and-glove distribution in the distal extremities. Sensory symptoms may be negative or positive, diffuse or focal. Negative sensory symptoms include feelings of numbness or deadness, which patients may describe as being akin to wearing gloves or socks. Loss of balance, especially with the eyes closed, and painless injuries due to loss of sensation are common. Positive symptoms may be described as burning, prickling pain, tingling, electric shock–like feelings, aching, tightness, or hypersensitivity to touch.

Motor symptoms

Motor problems may include distal, proximal, or more focal weakness. In the upper extremities, distal motor symptoms may include impaired fine hand coordination and difficulty with tasks such as opening jars or turning keys. Foot slapping and toe scuffing or frequent tripping may be early symptoms of foot weakness. Symptoms of proximal limb weakness include difficulty climbing up and down stairs, difficulty getting up from a seated or supine position, falls due to the knees giving way, and difficulty raising the arms above the shoulders.

In the most common presentation of diabetic neuropathy with symmetrical sensorimotor symptoms, minor weakness of the toes and feet may be seen; severe weakness is uncommon and should prompt investigation into other causes, such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), or vasculitis. More severe weakness may be observed in asymmetrical diabetic neuropathy syndromes. Motor neuropathy may occur along with sensory neuropathy (sensorimotor neuropathy).

Autonomic symptoms

Autonomic neuropathy may involve the cardiovascular, gastrointestinal, and genitourinary systems and the sweat glands. Patients with generalized autonomic neuropathies may report ataxia, gait instability, or near syncope/syncope. In addition, autonomic neuropathies have further symptoms that relate to the anatomic site of nerve damage—gastrointestinal, cardiovascular, bladder, or sudomotor.

Gastrointestinal autonomic neuropathy may produce the following symptoms[46] :

  • Dysphagia

  • Abdominal pain

  • Nausea/vomiting

  • Malabsorption

  • Fecal incontinence

  • Diarrhea

  • Constipation

Cardiovascular autonomic neuropathy may produce the following symptoms[47] :

  • Persistent sinus tachycardia

  • Orthostatic hypotension

  • Sinus arrhythmia

  • Decreased heart variability in response to deep breathing

  • Near syncope upon changing positions from recumbent to standing

Bladder neuropathy (which must be differentiated from prostate or spine disorders) may produce the following symptoms:

  • Poor urinary stream

  • Feeling of incomplete bladder emptying

  • Straining to void

Sudomotor neuropathy may produce the following symptoms:

  • Heat intolerance

  • Heavy sweating of head, neck, and trunk with anhidrosis of lower trunk and extremities

  • Gustatory sweating

Physical Examination

Physical examination of patients with suspected distal sensory, motor, or focal (ie, entrapment or noncompressive) neuropathic symptoms should include assessments for both peripheral and autonomic neuropathy.[48]

Peripheral neuropathy testing

Testing for peripheral neuropathy begins with assessment of gross light touch and pinprick sensation. The first clinical sign that usually develops in diabetic symmetrical sensorimotor polyneuropathy is decrease or loss of vibratory and pinprick sensation over the toes. As disease progresses, the level of decreased sensation may move upward into the legs and then from the hands into the arms, a pattern often referred to as "stocking and glove" sensory loss. Very severely affected patients may lose sensation in a "shield" distribution on the chest.

Vibratory sense in the feet is tested with a 128-Hz tuning fork placed at the base of the great toenail. Test protective sensation with 5.07 Semmes-Weinstein monofilament, briefly applying the tip perpendicular to the plantar surface of the foot, using sufficient force (10 g) to buckle the monofilament. Inability to perceive the tuning fork or the monofilament identifies patients who are at increased risk (ie, 60% in the next 3 years) of developing a foot ulcer.[49] The 2 tests should be performed at least every year.[50]

Test deep tendon reflexes. With neuropathy, these are commonly hypoactive or absent. Perform strength testing and examine for distal intrinsic extremity muscle atrophy, since weakness of small foot muscles may develop. Check dorsal pedal and posterior tibial pulses.

Examine the skin for dryness, tinea pedis, cracks, onychomycoses, acute erythema and tenderness, and fluctuance under calluses.

Perform Tinel testing. Paresthesias or pain suggests median nerve injury.

Perform cranial nerve testing. Have the patient walk on the heels and toes; heel-toe walking tests not only distal lower-extremity strength but balance, as well.

Perkins et al recommended conducting annual screening for diabetic neuropathy using superficial pain sensation testing, monofilament testing, or vibration testing by the on-off method. These researchers also validated a scoring system to document and monitor neuropathy in the clinic.[51] Dyck et al described case report forms for recording symptoms and signs of neuropathy that might be useful in longitudinal follow-up of individual patients.[52]

Autonomic neuropathy testing

Testing for autonomic neuropathies is performed objectively in a specialized autonomic laboratory, evaluating cardiovagal, adrenergic, and sudomotor function. However, the clinician may first perform bedside screening to assess if further, more specialized testing is necessary.

Blood pressure and heart rate measurements with the patient supine and upright are compared. Blood pressure measurements in patients with autonomic neuropathy may show orthostatic hypotension with reduced compensatory tachycardia. Testing for orthostatic hypotension is particularly important in patients with longstanding diabetes mellitus.[53]

The sinus arrhythmia (SA) ratio is measured with the patient breathing 6 times per minute while the heart rate is monitored with a continuous ECG strip. The longest R-R interval during expiration and the shortest R-R interval during inspiration are measured, and the average of the 6 breaths is taken. The SA ratio is R-R expiration/R-R inspiration. The normal ratio is 1:2.

Classification of Diabetic Neuropathy

Diabetic neuropathies are heterogeneous in type; thus, several classifications of diabetic neuropathy have been created and recognized.[54, 2, 48] Two classification systems will be presented here: the Thomas system and symmetrical-versus-asymmetrical neuropathies.

Thomas system

A classification system by Thomas[55] combines anatomy and pathophysiology. It is presented below with a few modifications:

  • Hyperglycemic neuropathy (acute)

  • Generalized symmetrical polyneuropathies

  • Sensory neuropathy

  • Sensorimotor neuropathy (chronic, symmetric)

  • Autonomic neuropathy (cardiovascular, gastrointestinal, genitourinary, sudomotor)

  • Focal and multifocal neuropathies: this category includes cranial neuropathy, proximal motor neuropathy (amyotrophy), thoracic or lumbar radiculopathies, and focal limb neuropathies (entrapment neuropathies)

  • Superimposed chronic inflammatory demyelinating polyneuropathy (CIDP)

Symmetrical versus asymmetrical neuropathies

Another generally accepted classification of diabetic neuropathies divides them broadly into symmetrical and asymmetrical neuropathies.

Symmetrical polyneuropathies involve multiple nerves diffusely and symmetrically. Distal symmetrical sensorimotor polyneuropathy is the most common manifestation of diabetic neuropathy. The syndrome has been defined in many ways, but 3 key criteria are commonly accepted:

  • The patient must have diabetes mellitus by one of the widely accepted definitions such as those outlined by the American Diabetes Association or World Health Organization[56, 57]

  • The severity of polyneuropathy should be commensurate with the duration and severity of the diabetes

  • Other causes of sensorimotor polyneuropathy must be excluded

Distal symmetrical sensorimotor polyneuropathy affects sensory, motor, and autonomic functions in varying degrees, with sensory abnormalities predominating. Chronic symmetrical symptoms affect peripheral nerves in a length-dependent pattern, with the longest nerves affected first. Patients commonly present with painful paresthesias and numbness, which begin in the toes and ascend proximally in a stocking-like distribution over months and years.

When sensory symptoms ascend above the knees, similar symptoms develop in the hands, progressing proximally in a glove-like distribution. At a very late stage, the anterior aspect of the trunk and vertex of the head may be affected. The loss of sensation in the feet predisposes to development of foot ulcers and gangrene.[58] In addition, mild weakness of foot muscles and decreased ankle and knee reflexes occur commonly. With impaired proprioception and vibratory perception, gait may be affected (sensory ataxia).

Small-fiber neuropathy is a distal symmetrical neuropathy involving predominantly small-diameter sensory fibers (A delta and C fibers). It manifests as painful paresthesias that patients perceive as burning, stabbing, crushing, aching, or cramplike, with increased severity at night. There is loss of pain and temperature sensation with relative sparing of distal reflexes and proprioception.

Although some degree of autonomic involvement is present in most patients with distal symmetrical diabetic polyneuropathy, patients may not notice autonomic problems, and pure autonomic diabetic neuropathy is rare. Manifestations of autonomic neuropathy may include orthostatic hypotension, resting tachycardia, loss of normal sinus arrhythmia ratio, anhidrosis, bowel or bladder dysfunction, and small pupils sluggishly reactive to light.

In diabetic neuropathic cachexia, the patient experiences a precipitous and profound weight loss followed by severe and unremitting cutaneous pain, small-fiber neuropathy, and autonomic dysfunction. This condition occurs more often in older men; impotence is common. Muscle weakness is uncommon. The condition usually improves with prolonged glycemic control; however, symptoms are often refractory to other pharmacologic treatment. Limited anecdotal improvement is reported with nonpharmacologic treatments such as sympathectomy, spinal cord blockade, and electrical spinal cord stimulation. Recovery may be incomplete and prolonged over many months

Asymmetrical neuropathies include single or multiple cranial or somatic mononeuropathies. Syndromes include the following:

  • Median neuropathy of the wrist (carpal tunnel syndrome)

  • Other single or multiple limb mononeuropathies

  • Thoracic radiculoneuropathy

  • Lumbosacral radiculoplexus neuropathy

  • Cervical radiculoplexus neuropathy

These syndromes are distinguished from typical distal diabetic polyneuropathy by the following characteristics:

  • They often have a monophasic course

  • Some are associated with inflammatory angiitis and ischemia (eg, lumbosacral radiculoplexus neuropathy) and may appear acutely or subacutely

  • They have a weaker association with total hyperglycemic exposure than symmetrical polyneuropathies

Cranial mononeuropathy most often involves cranial nerves (CN) III, IV, VI, VII, or II. Disease of CN III, IV, and VI manifests as acute or subacute periorbital pain or headache followed by diplopia. Muscle weakness is typically in the distribution of a single nerve, and pupillary light reflexes are usually spared. Complete spontaneous recovery usually occurs within 3 months.

Facial neuropathy manifests as acute or subacute facial weakness (taste is not normally affected) and can be recurrent or bilateral. Most patients recover spontaneously in 3-6 months.

Anterior ischemic optic neuropathy manifests as acute visual loss or visual-field defects (usually inferior altitudinal). The optic disc appears pale and swollen; flame-shaped hemorrhages may be present.

For more information, see Macular Edema, Diabetic.

Somatic mononeuropathies include focal neuropathies in the extremities caused by entrapment or compression at common pressure points or by ischemia and subsequent infarction. Entrapment and compression tend to occur in the same nerves and at the same sites as in individuals without diabetes. Median nerve entrapment at the wrist (carpal tunnel syndrome) is more common in patients with diabetes and can be treated in the same manner as in patients without diabetes. Symptoms are often bilateral. The susceptibility to ulnar nerve entrapment at the elbow or common peroneal nerve entrapment at the fibular head is not definitely increased among patients with diabetes.

Neuropathy secondary to nerve infarction presents acutely, usually with focal pain associated with weakness and variable sensory loss in the distribution of the affected nerve. Multiple nerves may be affected (mononeuritis multiplex).

Diabetic thoracic radiculoneuropathy presents as burning, stabbing, boring, beltlike, or deep aching pain that usually begins unilaterally and may subsequently become bilateral. Skin hypersensitivity and allodynia (pain with normally innocuous touch) may occur. Numbness follows a dermatomal distribution, most prominent in distal distribution of intercostal nerves. Single or multiple spinal roots are involved. Contiguous territorial extension of symptoms may occur in a cephalad, caudal, or contralateral direction. In the trunk, thoracoabdominal neuropathy or radiculopathy may cause chest and/or abdominal pain in the distribution of thoracic and/or upper lumbar roots. Weakness presents in the distribution of the affected nerve root, such as bulging of the abdominal wall from abdominal muscle paresis (thoracic root). Patients older than 50 years are affected most often; it is more common in diabetes mellitus type 2 and is often associated with significant weight loss. There isoftencoexistingdiabeticdistalsymmetrical polyneuropathy.

Diabetic radiculoplexus neuropathy may occur in the cervical or lumbosacral distributions and is referred to in the literature by various designations, including diabetic amyotrophy, Bruns-Garland syndrome, and diabetic plexopathy. The most frequent initial symptom is sudden, severe, unilateral pain in the hip/lower back or shoulder/neck. Weakness then develops days to weeks later. Atrophy of the limb musculature may occur. Allodynia, paresthesias, and sensory loss are common.

Symptoms usually begin unilaterally and may later spread to the opposite side. Reflexes in the affected limb may be depressed or absent. This condition often occurs in patients older than 50 years with poorly controlled diabetes. It is more common in men than in women. Significant weight loss occurs in 50% of patients. The course is generally monophasic, with improvement over many months; however, some residual deficits often remain.

For more information, see Diabetic Lumbosacral Plexopathyhere.

Staging

Different clinical neurologic scales can be used to assess the severity of diabetic polyneuropathy.[54]

A common staging scale of diabetic polyneuropathy is as follows[59] :

  • NO - No neuropathy

  • N1a - Signs but no symptoms of neuropathy

  • N2a - Symptomatic mild diabetic polyneuropathy; sensory, motor, or autonomic symptoms; patient able to heel walk

  • N2b - Severe symptomatic diabetic polyneuropathy (as in N2a, but patient unable to heel walk)

  • N3 - Disabling diabetic polyneuropathy

 

DDx

Diagnostic Considerations

Establishing the diagnosis of diabetic neuropathy requires careful evaluation, because in 10-26% of diabetic patients with neuropathy, the neuropathy may have another cause.[33, 60, 61, 62, 63]

The differential diagnoses to consider vary with the presentation.

Cranial mononeuropathy includes the following:

  • Intracranial aneurysms

  • Bell palsy

Thoracoabdominal neuropathy includes the following:

  • Herpes zoster

  • Spinal tumors

  • Myocardial infarction

  • Acute cholecystitis

  • Acute appendicitis

  • Diverticulitis

Lumbosacral radiculoplexopathy includes the following:

  • Anterior disk protrusion

  • Spinal cord tumors

  • Malignant nerve root infiltrations

  • Inflammatory neuropathies

Peripheral neuropathy includes the following:

  • Pernicious anemia

  • Vitamin B-6 intoxication

  • Alcoholism

  • Uremia

  • Chemical toxins

  • Nerve entrapment and compression of benign etiology

  • Hepatitis

  • Idiopathic

  • Congenital (various hereditary sensory motor neuropathies)

  • Paraneoplastic syndrome

  • Syphilis

  • HIV/AIDS

  • Medication (eg, chemotherapy, isoniazid)

  • Spine disease (eg, radiculopathy, stenosis, arteriovenous [AV] fistula)

Cardiovascular autonomic neuropathy (in addition to some listed above) includes the following:

  • Myocardial infarction

  • Neuropathic arrhythmias (eg, Wolff-Parkinson–White syndrome, sick sinus syndrome)

  • Volume depletion

  • Drugs

Gastrointestinal neuropathy includes the following:

  • Gastrointestinal malignancy

  • Peptic ulcer disease

  • Postsurgical vagotomy

  • Electrolyte imbalance

Bladder dysfunction includes the following:

  • Bladder outlet obstruction

  • Prostate cancer

  • Spinal cauda equine syndrome

Mononeuropathy includes the following:

  • Vasculitides

  • Acromegaly

  • Coagulopathies

  • Hypothyroidism

For more information, see Diabetic Lumbosacral Plexopathy.

Differential Diagnoses

 

Workup

Approach Considerations

Fasting plasma glucose and hemoglobin A1c are important laboratory screening tests for diabetic neuropathy.

Imaging studies rarely help the physician diagnose or manage diabetic neuropathy. However, in the appropriate clinical setting, MRI of the cervical, thoracic, and/or lumbar regions may help exclude another cause for symptoms mimicking diabetic neuropathy.

Multiple consensus panels recommend the inclusion of electrophysiologic testing in the evaluation of diabetic neuropathy. An appropriate array of electrodiagnostic tests includes both nerve conduction testing and needle EMG of the most distal muscles usually affected.

In a systematic review of 5 studies of noninvasive screening tools for detecting peripheral neuropathies in pediatric patients with type 1 diabetes, Hirschfeld and colleagues found that the diagnostic utility of the Rydel-Seiffer tuning fork and 10-g Semmes-Weinstein monofilament was low, while that of biothesiometry and a finer (1-g) monofilament was acceptable. Sensitivities and specificities of these screening tools were as follows:[64, 65]

  • Tuning fork: 87-99% (sensitivity); 1-19% (specificity)

  • Coarse monofilament: 16% (sensitivity); 64% (specificity)

  • Fine monofilament: 73% (sensitivity); 87% (specificity)

  • Biothesiometer: 61-80% (sensitivity); 64-76% (specificity)

Hemoglobin A1c and Fasting Plasma Glucose

Hemoglobin A1c and fasting plasma glucose are important laboratory screening tests for diabetic neuropathy. Hemoglobin A1c measurement is useful to assess the adequacy of recent diabetes control; levels are likely to be elevated in patients with diabetic neuropathies. In some cases, especially with asymmetrical syndromes, the severity of the elevation does not always correlate with the severity of the nerve disease.

A 3-hour glucose tolerance test may be more sensitive in borderline cases. A urinalysis is also helpful to screen for nephropathy and proteinuria.

Basic Laboratory Screening Tests

Testing is tailored depending on the clinical presentation. Examples of tests suggested as basic screening tools to exclude common causes of neuropathy other than diabetes include the following:

  • Complete blood cell count

  • Complete metabolic panel (electrolytes and liver function panel)

  • Vitamin B-12 and folate levels

  • Thyroid function tests

  • Erythrocyte sedimentation rate

  • C-reactive protein

  • Serum protein electrophoresis with immunofixation electrophoresis

  • Antinuclear antibody

  • Anti-SSA and SSB antibodies

  • Rheumatoid factor

  • Paraneoplastic antibodies

  • Rapid plasma reagin

  • Genetic screens

  • Hematology screen to check for anemia

  • Sequential multiple analysis-7 (SMA7) to check renal function and electrolyte imbalances/complete metabolic panel (CMP)

For more information, see Type 2 Diabetes and TCF7L2.

Electromyography and Nerve Conduction Studies

Nerve conduction studies (NCS) and electromyography (EMG) can document the characteristics of the neuropathy (eg, axonal, demyelinating) and the localization (eg, mononeuropathy versus radiculopathy or distal neuropathy) and, possibly, the severity and even prognosis for morbidity. Multiple consensus panels recommend the inclusion of electrophysiologic testing in the evaluation of diabetic neuropathy. These same panels recommend the use of nerve conduction velocity (NCV)/EMG procedures in clinical research studies. An appropriate array of electrodiagnostic tests includes both nerve conduction testing and needle EMG of the most distal muscles usually affected.

Conventional nerve conduction velocity studies

Conventional NCV testing includes measurement of the speed of both motor and sensory conduction. The amplitude of the distal response is also measured. The proximal component of conduction can be investigated with H-reflex (S1 root) or F-wave (motor pathways only) response.

Needle electromyography

Needle EMG is performed in the distal muscles in cases of generalized neuropathy and entrapment, in the proximal limb muscles in amyotrophy, and in the paraspinal and limb muscles in suspected radiculopathy. The examiner searches for abnormal spontaneous potentials, voluntary motor unit recruitment, and motor unit configuration. In weak patients, the recruitment characteristics can often help distinguish a neuropathic from a myopathic process.

Nerve conduction study findings

Findings on nerve conduction studies depend on the pattern of nerve damage. Patients with distal symmetrical sensorimotor polyneuropathy from predominant axonal loss have reduced or absent sensory nerve action potentials, especially in the legs. With progression of neuropathy, compound motor action potential amplitudes may also be reduced and abnormalities may be observed in the hands. These changes reflect length-dependent degeneration of large-diameter myelinated nerve fibers.

Conduction velocities are generally within the normal range or only mildly slowed in distal symmetrical polyneuropathy. If conduction velocities are less than 70% of the lower limit of normal, or if conduction block is present, the patient may have superimposed peripheral nerve demyelination in addition to the more typical axonal loss seen in distal symmetrical polyneuropathy. Generalized demyelinating changes on nerve conduction studies should prompt further evaluation for CIDP. Focal slowing of conduction velocity at common sites of entrapment may indicate one of the mononeuropathy syndromes discussed above.

In patients with diabetes, nerve conduction study abnormalities may be found even in the absence of clinical symptoms of polyneuropathy. In a prospective study by Walter-Höliner et al of 38 children and adolescents with type 1 diabetes, clinical neurologic examination revealed diabetic peripheral neuropathy in 13.2% of the group, compared with 31.6% of patients when diagnosis was made using nerve conduction velocity testing. Thus, the latter test demonstrated the widespread existence of subclinical diabetic peripheral neuropathy in the study’s patients.[66]

Electromyographic sampling of distal lower extremity muscles may reveal acute and ongoing denervation in the form of positive sharp waves and fibrillation potentials (spontaneous discharges). Reinnervation changes such as large-amplitude, long-duration, and polyphasic motor unit potentials reflect chronicity. Abnormalities in paraspinal muscles (eg, spontaneous discharges) usually reflect disease in spinal nerve roots.

Some studies have proposed that the severity of electrophysiologic abnormalities not only correlates with symptoms but also predicts the level of morbidity related to DM. Most authors suggest the NCV results to be stable or worsening over time; however, in 1998, Tkac found that the NCV levels could improve with glycemic control.[67]

Electrophysiologic Studies

Electrophysiologic studies are the most sensitive, reliable, and reproducible measures of nerve function.[68] Electrophysiologic findings usually correlate with morphologic changes on nerve biopsy. Common early findings are abnormal nerve conduction studies or reduced variability of heart rate with deep breathing or Valsalva maneuver. Although electrodiagnostic studies can characterize and quantitate nerve dysfunction, they cannot distinguish diabetic neuropathy from neuropathy of other causes.

Composite scores, combining clinical, quantitative sensory,[38] and electrophysiologic measures, are often used in natural history and efficacy studies. Examples include the Neuropathy Impairment Score in the Lower Limbs + 7 and the Michigan Diabetic Neuropathy score.[48, 69]

MRI and CT

Plexus MRI may be helpful to exclude other problems (eg, tumor) in patients with radiculoplexus neuropathy syndromes. For patients who cannot have MRI, CT myelography is an alternative to exclude compressive lesions and other pathology in the spinal canal. In cranial nerve palsies, brain imaging, usually with MRI, is helpful to exclude intracranial aneurysms, compressive lesions, and infarcts.

Nuclear Imaging

Scintigraphic techniques are used to detect and quantify cardiac autonomic neuropathy (for research purposes). Techniques include radiolabeled analogs of norepinephrine, 123I-metaiodobenzylguanidine (MIBG), and 11C-hydroxyephedrine. Adrenergic nerve terminals of the heart actively take up these compounds. Combining this technique with single-photon emission computed tomography (SPECT) scanning allows detection of decreased innervation of the heart.

Doppler Imaging

Laser Doppler can be used to measure skin perfusion. In this test, skin blood flow is measured by continuous laser Doppler assessment in response to several stimuli.

Microdialysis

Microdialysis has been used to study nitric oxide release, which participates in vasodilation of the microvasculature. In this test, probes are inserted into the dermis (with an ISO-NO Mark II oxide meter, a microsensor that measures nitric oxide release from single cells).

Electrocardiography

Electrocardiography may reveal prolongation of the QT interval. This is secondary to imbalance between right and left heart sympathetic innervation. This abnormality is thought to increase risk of arrhythmias. A screening ECG is advisable for patients with longstanding DM.

Nerve and Skin Biopsy

A nerve biopsy can be obtained, typically of the sural nerve, to confirm and help diagnose the neuropathic stage (ie, mild, moderate, severe). However, this is an invasive procedure and carries the risk of producing chronic pain, numbness, and cold insensitivity in the distribution of the sural nerve. Thus, with NCV/EMG and QST available, the sural nerve biopsy is rarely needed for diagnostic purposes any longer.

A skin biopsy can be obtained for research purposes only. Immunohistochemistry is used to quantify the cutaneous nerves to provide a morphologic assessment of diabetic neuropathies. This tool is new for clinical research, and it is used as an endpoint in diabetic neuropathy. The procedure requires only a 3-cm skin biopsy and enables a direct study of small nerve fibers (ie, C-fibers) that produce pain and temperature sensation.

Biopsy rarely is recommended for clinical purposes. Reasons for this move away from biopsies in clinical trials include the invasive nature of the procedure with its attendant risks, discomfort to the patient, cost, problems with reproducibility due to sampling error, and availability of other methods to obtain similar information. This study is performed primarily when the etiology of the neuropathy is in question or in research settings. Several studies have looked at biopsies, mainly of the sural nerve in humans. These studies were performed in advanced neuropathy; vessels were found to be thickened, and nerves were found to have undergone severe damage. Indications of nerve regrowth were small and weak.

Future Approaches

The following additional diagnostic approaches for diabetic neuropathy are currently in use or under intense study. Details of these techniques are beyond the scope of this review.

  • Skin punch biopsy/intraepidermal nerve fiber density testing[70] and immunohistochemical staining of peripheral nerves

  • Quantitative sensory testing

  • Imaging using MRI and ultrasonography

 

Treatment

Approach Considerations

Management of diabetic neuropathy should begin at the initial diagnosis of diabetes. The primary care physician needs to be alert for the development of neuropathy—or even its presence at the time of initial diabetes diagnosis—because failure to diagnose diabetic polyneuropathy can lead to serious consequences, including disability and amputation.[71, 72, 73, 74]

Consider any patient with clinical evidence of diabetic peripheral neuropathy to be at risk for foot ulceration, and provide education on foot care.[75] If necessary, refer the patient to a podiatrist. Admit patients for an infected diabetic foot ulcer or gangrene.

For more information, see Diabetic Foot.

For more information, see Diabetic Foot Infections.

Patients with diabetic peripheral neuropathy require more frequent follow-up, with particular attention to foot inspection to reinforce the need for regular self-care. The provision of regular foot examinations and reinforcement of the educational message on foot care have been shown in several studies to significantly reduce rates of ulceration and even amputation.[76]

The primary care physician is responsible for educating patients about the acute and chronic complications of diabetes,[49] including the psychological impact of sexual dysfunction in both men and women. The importance of involving a neurologist (preferably with expertise in peripheral neuropathy) in the treatment of patients with diabetic neuropathy cannot be overemphasized.

Glycemic Control

Of all treatments, tight and stable glycemic control is probably the most important for slowing the progression of neuropathy.[77] Because rapid swings from hypoglycemia to hyperglycemia have been suggested to induce and aggravate neuropathic pain, the stability of glycemic control may be as important as the actual level of control in relieving neuropathic pain. The Diabetes Control and Complications Trial (DCCT) demonstrated that tight blood sugar control in patients with type 1 diabetes decreased the risk of neuropathy by 60% in 5 years.[24, 78] The effect of tight glycemic control on polyneuropathy in patients with type 2 diabetes or those with impaired glucose tolerance/impaired fasting glucose is not as clear and requires further prospective study.[79]

A 2012 Cochrane review indicates that tight glycemic control prevents the development of clinical neuropathy and reduces nerve conduction and vibration threshold abnormalities in patients with either type 1 or type 2 diabetes. However, tight glucose control also increases the risk of severe hypoglycemic episodes, and this should be considered when assessing its risk/benefit ratio.[80]

Diabetic Neuropathic Pain Management

Many medications are available for the treatment of diabetic neuropathic pain. Oral agents include antidepressants and anticonvulsant drugs. According to the 2011 guideline issued by the American Academy of Neurology (AAN), American Academy of Physical Medicine and Rehabilitation (AANEM) and the American Academy of Physical Medicine and Rehabilitation (AAPMR) guideline for the treatment of painful diabetic neuropathy (PDN), pregabalin is recommended for treatment of diabetic neuropathic pain. The drug has been proven effective and can improve quality of life. However, physicians should determine if the drug is clinically appropriate for their patients on a case-by-case basis. Gabapentin and sodium valproate should also be considered for diabetic neuropathy pain management.

According to a Cochrane review evaluating gabapentin for chronic neuropathic pain and fibromyalgia, gabapentin leads to significant pain relief in patients with chronic neuropathic pain when compared with a placebo. Although patients frequently experience adverse side effects, these are usually tolerable, and serious side effects were not increased when compared with side effects associated with the placebo.[81]

According to the 2011 AAN/AANEM/AAPMR guideline, dextromethorphan, morphine sulfate, tramadol, and oxycodone should be considered for PDN treatment. No one opioid is recommended over another.

Topical therapy with capsaicin or transdermal lidocaine may be useful in some patients, especially those with more localized pain or those in whom interactions with existing oral medications is a concern. The 2011 AAN/AANEM/AAPMR guideline recommends that both of these agents be considered in for treatment of PDN. In clinical trials, capsaicin has been effective in reducing pain in PDN, but many patients cannot tolerate the side effects, such as burning pain on contact with warm/hot water or in hot weather. Any of these medications may be associated with adverse effects, and patients should be counseled about possible problems before initiating treatment.[82, 61] Patients should be assessed every 6 weeks so that adverse effects can be monitored if possible. Decrease or increase drug dose if indicated.

For many of these medications, use for neuropathic pain is off-label; they were approved by the Food and Drug Administration for other indications. Many are in the news for questionable side effects (eg, increased blood pressure and edema from salt retention with fludrocortisones). Nevertheless, multiple clinical studies show benefit for the use of these medications in the treatment of neuropathic pain. Use of these medications is well within the standard of care in most medical communities. A number of medications are currently undergoing evaluation in clinical trials. Some are licensed for use in other countries.

In a review of 6 trials (2220 patients) on duloxetine's effects on painful diabetic peripheral neuropathy (3 trials) and fibromyalgia (3 trials), Lunn et al concluded that 60 mg of duloxetine daily can relieve the pain of peripheral neuropathy in the short-term, calculating a 1.65 risk ratio for a 50% pain reduction at 12 weeks.[83] Adverse events were common and dose dependent, according to the authors, but serious ones were rare. The 2011 AAN/AANEM/AAPMR guideline recommends considering the antidepressants amitriptyline, venlafaxine, and duloxetine for the treatment of PDN, although data are insufficient to recommend one of these agents over the others.

There was no difference identified between gabapentin and tricyclic antidepressants in the achievement of pain relief of diabetic neuropathy or postherpetic neuralgia in a study by Chou et al. The authors performed a meta-analysis of head-to-head trials comparing the results of gabapentin and tricyclic antidepressants for pain relief in diabetic neuropathy.[84] . Pregabalin has similar efficacy as gabapentin for most part.

Pain Control in Pregnancy

During pregnancy, prescribing medicine for pain control is difficult. The best hope for pain control in rare cases of young women with severe neuropathy is to control their blood glucose diligently and try to control pain with acetaminophen. At the end of the third trimester, the physician can prescribe amitriptyline, gabapentin, and other medications as indicated if the benefit clearly outweighs the risk to the fetus. Physical therapy may be effective in pregnant patients by increasing their circulation.

To see complete information on Diabetes Mellitus and Pregnancy, please visit our main article.

Diabetic Gastroparesis

Erythromycin and metoclopramide are used to treat diabetic gastroparesis. Additionally, MiraLax (polyethylene glycol 3350) is gaining increasing popularity as the first-line agent for severe constipation and lower motor unit bowel.[46]

A newer agent, tegaserod (Zelnorm), may be helpful in patients with chronic ileus. In early 2010, however, tegaserod marketing was suspended because of a meta-analysis showing an excess number of serious cardiovascular adverse events, including angina, myocardial infarction, and stroke, in those taking tegaserod compared with placebo. Tegaserod is currently available only on an emergency basis. For more information, see the FDA Postmarket Drug Safety Information for Patients and Providers.

Dietary Supplements

Vitamin supplementation is being studied to see if that can have an impact. One study of zinc sulfide showed improvement in glycemic control in 60 patients.[85] Certain B vitamins are often prescribed in an attempt to reduce paresthesias.

Experimental Therapies

Aldose reductase inhibitors

Aldose reductase inhibitors block the rate-limiting enzyme in the polyol pathway that is activated in hyperglycemic states. Numerous studies of aldose reductase inhibitors (eg, alrestatin, sorbinil, tolrestat, epralrestat) have been published in the past 30 years, but many of the earlier trials had problems related to poor study design (eg, enrolling patients with advanced neuropathy who were unlikely to benefit from treatment).

These medications are not currently available in the United States.[86, 87] Epralrestat is currently marketed only in Japan. Epalrestat reduces intracellular sorbitol accumulation, which has been implicated in the pathogenesis of late-onset complications of diabetes mellitus. Epalrestat 150 mg/day for 12 weeks improved motor and sensory nerve conduction velocity and vibration threshold compared with baseline and placebo in patients with diabetic neuropathy. Subjective symptoms, including pain, numbness, hyperesthesia, coldness in the extremities, muscular weakness, dizziness, and orthostatic fainting, were also improved.[88, 89]

Alpha-lipoic acid

In a multicenter placebo-controlled trial of the antioxidant alpha-lipoic acid, Ziegler and colleagues reported short-term symptomatic relief of neuropathy symptoms in patients with type 2 diabetes and symptomatic neuropathy.[18] Other studies of this drug are ongoing.

Actovegin

A deproteinized derivative of calf blood, actovegin contains inorganic substances (eg, electrolytes, trace elements) and organic components (eg, amino acids, oligopeptides, nucleosides, glycosphingolipids). Actovegin also contains inositol phospho-oligosaccharides (IPOs), which are thought to elicit central and peripheral insulin effects. Ziegler et al found that treatment with actovegin improved neuropathic symptoms, vibration perception threshold, sensory function, and quality of life in 567 patients with type 2 diabetes mellitus and diabetic polyneuropathy. In this multicenter, randomized, double-blind trial, sequential intravenous (2000 mg/d) and oral (1800 mg/d) actovegin treatment was given over 160 days.[82]

Spinal cord stimulators and other therapies

Pain medicine specialists have been experimenting with spinal cord stimulator implants in severely painful cases.[90] One such study of 10 patients showed that median background and peak pain scores at the end of the study were, respectively, 77 and 81 with the stimulator off and 23 and 20 with the stimulator on. Exercise tolerance significantly improved at 3 months (n = 7, median increase 85%) and at 6 months. Further study is necessary.[91] Alternative and complementary therapies for pain (eg, acupuncture) are under investigation.[92, 21]

Treatment of Autonomic Dysfunction

Erectile dysfunction

Although several modalities are available, erectile dysfunction from diabetic neuropathy is a very difficult condition to treat. All other causes of impotence must be excluded. Once the diagnosis has been confirmed, the oral agent sildenafil Viagra) and related phosphodiesterase type 5 (PDE5) inhibitors can be used (if not contraindicated in the patient). Older methods such as vacuum devices or intracavernosal papaverine injections may be tried. Referral to a urologist is suggested.

Orthostatic hypotension

Symptomatic orthostatic hypotension can be troubling in patients with diabetic neuropathy. Increasing the dietary fluid and salt intake, along with use of compression stockings, may help. If these modalities do not improve symptoms, then medication may help.[53]

Gustatory sweating

Glycopyrrolate is an antimuscarinic compound that can be used for the treatment for diabetic gustatory sweating. When applied topically to the affected area, it results in a marked reduction in sweating while eating a meal.

Surgical Treatment

Surgery is indicated in patients with infected foot ulcers when the infection cannot be controlled medically. Aggressive debridement or amputation may be necessary if signs of necrosis or infection do not improve with IV antibiotics.[93, 94]

Jejunostomy may be performed in patients with intractable gastroparesis (ie, severe nausea and vomiting, severe weight loss). This will allow patients to be fed enterally, bypassing the paralytic stomach.

When impotence is a continual problem, the patient may pursue the option of a penile prosthesis.

The feet of patients with DM often become insensate and are highly susceptible not only to ulcers but also to the Charcot foot (ie, a foot that loses its structure secondary to trauma and acute arthropathy) from frequent and multiple traumas. Charcot foot, which occurs not only in diabetic peripheral neuropathy but in other types of severe neuropathy as well, can be treated with bracing or special boots. In some cases, surgery is used to correct the deformity.[95, 96]

For more information, see Perioperative Management of the Diabetic Patient.

For more information, see Diabetic Foot.

For more information, see Diabetic Foot Infections.

Pancreatic Transplantation

Pancreatic transplantation in patients with diabetes and end-stage renal disease can stabilize neuropathy and in some instances improve motor, sensory, and autonomic function for as long as 48 months after uremia plateaus.[76]

Rehabilitation

Physical therapy

Physical therapy may be a useful adjunct to other therapy, especially when muscular pain and weakness are a manifestation of the patient's neuropathy. The physical therapist can instruct the patient in a general exercise program to maintain his or her mobility and strength. An aquatic therapist can also be helpful.

Although the American Diabetes Association recommends moderate to vigorous exercise for patients with diabetes to help manage the disease, a literature review by Johnson and Takemoto indicated that in patients who have been inactive or cannot achieve such intensity levels, low-intensity aerobic therapy can improve sensation in the feet and reduce pain and tingling in the lower limbs.[97, 98]

In addition to exercise, the patient also should be educated on independent pain management and relaxation strategies to assist with pain control. Transcutaneous electrical nerve stimulation (TENS) may be a recommended modality for patients with neuropathic pain, and the physical therapist can be helpful in teaching and monitoring the patient in its use. In a 1999 case report, Somers and Somers found that application of TENS to the skin of the lumbar region was an effective treatment for the pain of diabetic neuropathy, but no controlled studies have confirmed this finding.[99] The 2011 AAN/AANEM/AAPMR guideline supports TENS as probably effective as a treatment for PDN.[100]

In cases of foot ulcers, physical therapy may be indicated for wound care. Treatments may consist of whirlpool, Unna boots (if necessary, although not commonly used), and debridement. For patients with autonomic neuropathy, balance training and fall prevention education is paramount.

Brace assessment and orthotic or prosthetic training are useful when appropriate, and walking-aid assessment and implementation may be necessary.

Occupational therapy

Occupational therapy may be necessary in cases where there is severe loss of functional status. When only the lower limbs are involved, patients may need home modifications and equipment. When the upper limbs are involved, patients may need more extensive functional restoration and adaptive equipment. When secondary complications require amputation of a limb, even more intensive functional retraining is required.

Speech therapy

Involvement of a speech therapist rarely is indicated, but professionals from this discipline can help with patients affected by gastroparesis or dysphagia.

Recreational therapy

A recreational therapist may help the patient with performance of community activities. Many patients with chronic disease, especially elderly patients, become isolated and are at risk for comorbid conditions such as depression.

Complications of Disease

Peripheral neuropathy can lead to foot ulcers and leg amputations. When a foot ulcer shows signs of infection (eg, thick yellow drainage, erythema around the wound, fever, necrotic tissue), the patient often fares much better by being admitted to a hospital, having the extent of infection assessed (eg, with MRI), and receiving IV antibiotics and foot debridement (if necessary).

Autonomic neuropathy is associated with dizziness and falling with resultant injuries, nausea and vomiting, severe diarrhea, and dehydration, all of which can lead to hyperosmolar nonketotic diabetic coma or diabetic ketoacidosis and death. Cardiovascular autonomic neuropathy can cause death.

Consultations

Most diabetic patients benefit from consultation with an endocrinologist at periodic intervals, and those with more brittle diabetes may benefit from regular endocrinology consultations to assist in diabetes management.

Patients with diabetes who develop neuropathy should see a neurologist early in the course of neuropathy. Patients with neuropathy symptoms or signs that seem out of proportion to the severity of diabetes should be evaluated by a neurologist to help exclude other underlying causes of neuropathy.

Physical medicine and rehabilitation physicians provide a functional-based comprehensive evaluation and treatment program for patients with diabetic neuropathy. Ulcer management may warrant consultation with a specialist at a wound clinic or perhaps a vascular surgeon. A cardiologist should monitor patients who have electrocardiographic abnormalities and/or suggestion of cardiac autonomic neuropathy. A gastroenterologist can monitor patients with intractable GI problems, such as gastroparesis and diarrhea.

Consultation with the appropriate specialist is also advisable if there are questions about the diagnosis of a particular form of neuropathy, or if the patient does not tolerate first-line medications.

Long-Term Monitoring

Patients with diabetic neuropathy should have regular monitoring by a primary care physician. Patients should be monitored every 4 weeks to 3 months to try to assess whether therapy is working to decrease pain or nausea or vomiting and also to taper off medications for painful peripheral neuropathy. Objective measures of function and improvement should be taken at every visit. Examine the patient's feet and assess with monofilament and tuning fork on every visit when the patient comes in for DM care. Monitoring patients closely for glycemic control is essential.[69]

Confocal microscopy of the cornea lends itself to longitudinally assessing progression of neuropathy. Furthermore, improvements in risk factors such as glycated hemoglobin (HbA1c) levels may be associated with morphological repair of nerve fibers.[101]

 

Medication

Medication Summary

For the treatment of diabetic neuropathy, acute cases may be able to be managed with standard analgesics, but other agents will likely be necessary for chronic pain. Occasionally, muscle relaxants may be of benefit in the first 2 weeks of therapy.

Each type of pain or a combination of pain types should be treated. Reevaluation of the painful neuropathy should be performed every 6 weeks.[102] Every effort should be made to taper and eventually to stop therapies. Therapies may need to be reinstated at later dates if symptoms flare up.

The pharmacologic agents listed below are commonly used for the symptomatic treatment of diabetic neuropathy. Most are not specifically approved by the United States Food and Drug Administration for this use, however.[18, 84, 86, 87, 71, 25, 20, 103, 104, 105]

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)

Class Summary

In patients with acute painful neuropathy, simple analgesics such as nonsteroidal anti-inflammatory drugs [NSAIDs] and acetaminophen may provide pain control.[102] They also may be used as first-line therapy in painful peripheral neuropathy. With chronic painful neuropathy, simple analgesics are typically not effective. More often, chronic neuropathic pain requires treatment with off-label medications.

Ibuprofen (Advil, Motrin IB)

NSAIDs may help decrease inflammation caused by diabetic neuropathy. They also decrease pain.

Naproxen (Naprosyn)

For relief of mild-to-moderate pain; inhibits inflammatory reactions and pain by decreasing activity of cyclo-oxygenase, which results in a decrease of prostaglandin synthesis.

Analgesic, Topical

Class Summary

Identifying the type of pain can direct the course of therapy. Dysesthetic pain can be relieved with capsaicin cream (Dolorac, Capsin, Zostrix) applied qid. Capsaicin cream may cause pain during the initial few applications; patients need to be made aware of this potential effect. Additionally, few patients comply with the frequent dosing, and the cream is messy on socks and shoes. Several recent studies have advocated topical administration of lidocaine as treatment of postherpetic neuralgia. Lidocaine gel (5%) in placebo-controlled study showed significant relief in 23 patients studied. Lidocaine tape also decreases severity of pain.

Capsaicin cream (Zostrix)

Natural chemical derived from plants of Solanaceae family. By depleting and preventing reaccumulation of substance P in peripheral sensory neurons, may render skin and joints insensitive to pain. Substance P thought to be chemomediator of pain transmission from periphery to CNS.

Anticonvulsant

Class Summary

Gabapentin (Neurontin) has been reported to work excellently in the treatment of dysesthetic pain.[103] Carbamazepine (Tegretol, Carbatrol, Epitol) has been used mainly for partial seizures and can be used in peripheral neuropathy as a third-line agent if all other agents fail to reduce or improve symptoms of diabetic neuropathy. Carbamazepine is a potentially effective treatment for chronic neuropathic pain.[106] However, the studies evaluating carbamazepine for chronic neuropathic pain must be interpreted with caution.

Pregabalin (Lyrica) is approved for the treatment of pain due to generalized diabetic peripheral neuropathy and may be considered as a first-line agent in diabetic peripheral neuropathic pain.[107]

In October 2017, the FDA approved Lyrica CR (pregabalin extended-release tablets) for the treatment of diabetic peripheral neuropathy, as well as postherpetic neuralgia. The agency based its approval of the drug, which is taken once daily, on the success of a randomized, placebo-controlled trial involving patients with postherpetic neuralgia, with pain intensity improving by at least 50% in 73.6% of those patients treated with Lyrica CR and in 54.6% of patients in the placebo group.[108]

According to the 2011 American Academy of Neurology (AAN)/American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM)/American Academy of Physical Medicine and Rehabilitation (AAPMR) guideline, lamotrigine (Lamictal) should probably not be recommended for diabetic neuropathy treatment due to relative inefficacy in pain control when compared with placebo.[109]

Gabapentin (Neurontin)

Excellent in treating pain described as dysesthetic, such as burning or pins and needles. Gabapentin should be used after all other first-line measures have been used without relief. This drug is a second-generation anticonvulsant. Gabapentin increases brain GABA levels, binds to the alpha2-delta subunit of voltage-gated calcium channels, and inhibits branched chain amino acid transferase.

Carbamazepine (Tegretol, Carbatrol, Epitol)

AED used mainly in partial seizures. Can be used in peripheral neuropathy as a third-line agent if all other agents fail to reduce or improve symptoms of diabetic neuropathy.

First-generation anticonvulsant. Slows the recovery rate of voltage-gated Na channels, minor Ca2+ channel antagonist effect, and is related chemically to tricyclic antidepressants.

Pregabalin (Lyrica, Lyrica CR)

FDA approved for the treatment of pain due to generalized diabetic peripheral neuropathy. The FDA has also approved the once-daily treatment Lyrica CR (pregabalin extended-release tablets) for the pain of diabetic peripheral neuropathy. Pregabalin is excellent in treating pain described as dysesthetic, such as burning or pins and needles. It may be considered as a first-line agent in diabetic peripheral neuropathic pain. This drug is also a second-generation anticonvulsant. Pregabalin binds to the alpha-2-delta subunit of voltage-gated calcium channels and inhibits branched chain amino acid transferase. This reduces inappropriate calcium influx into a hypersensitized cell.

Phenytoin (Dilantin)

May stabilize neuronal membranes and treat neuralgia by increasing efflux or decreasing influx of sodium ions across cell membranes in motor cortex during generation of nerve impulses. When serum level in or near therapeutic range, adjust dose in 30- to 50-mg increments. Small-dose increments may cause greater than expected increases in serum concentration (ie, Michaelis-Menten drug kinetics). Steady-state serum levels may take up to 3 wk to occur because half-life is concentration dependent.

Antidepressant, Tricyclic

Class Summary

For paresthetic pain, tricyclic antidepressants such as imipramine (Tofranil), nortriptyline (Pamelor, Aventyl), and amitriptyline (Elavil) have been shown to be useful as analgesics for paresthetic pain.[105]

Amitriptyline (Elavil)

By inhibiting reuptake of serotonin and/or norepinephrine by presynaptic neuronal membrane, may increase synaptic concentration in CNS. Useful as analgesic for certain types of chronic and neuropathic pain.

Imipramine (Tofranil)

This is the original TCA used for depression. These agents have been suggested to act by inhibiting reuptake of norepinephrine at synapses in central descending pain modulating pathways located in the brainstem and spinal cord.

Nortriptyline (Pamelor, Aventyl HCl)

Has demonstrated effectiveness in treatment of chronic pain; by inhibiting reuptake of serotonin and/or norepinephrine by presynaptic neuronal membrane, may increase synaptic concentration in CNS; pharmacodynamic effects such as desensitization of adenyl cyclase and down-regulation of beta-adrenergic receptors and serotonin receptors also appear to be involved in mechanisms of action.

Antidepressant, Selective Serotonin/norepinephrine Reuptake Inhibitor (SSNRI)

Class Summary

Duloxetine (Cymbalta) was the first medication to be approved specifically for the treatment of diabetic neuropathy. Venlafaxine (Effexor) has been recommended by the AAN/AANEM/AAPMR guidelines for consideration in diabetic neuropathy pain management.[110]

Duloxetine (Cymbalta, Drizalma Sprinkle)

Indicated for diabetic peripheral neuropathic pain. Potent inhibitor of neuronal serotonin and norepinephrine reuptake.

Antidepressant, Serotonin Reuptake Inhibitor

Class Summary

Paroxetine (Paxil) can be used as second-line or third-line treatment of painful diabetic neuropathy and is helpful in patients who are already depressed. Citalopram (Celexa) can be used as a second- or third-line therapy in neuropathy resulting from paresthesia.[105]

Citalopram (Celexa)

One of the newest antidepressants can be used as a second- or third-line therapy in neuropathy resulting from paresthesia.

Paroxetine (Paxil)

SSRI that can be used in second-line or third-line treatment of painful diabetic neuropathy; good for patients who already are depressed.

Antiarrhythmic Agent, Class I-b

Lidocaine anesthetic (Lidoderm)

Several recent studies have advocated topical administration of lidocaine as treatment of postherpetic neuralgia. Lidocaine gel (5%) in placebo-controlled study showed significant relief in 23 patients studied. Lidocaine tape also decreases severity of pain.

Prokinetic Agents

Class Summary

Medications for diabetic gastroparesis are erythromycin (E-Mycin, Erythrocin, Ery-Tab, E.E.S.), cisapride (Propulsid), and metoclopramide (Reglan, Maxolon, Clopra). However, in 2009 the FDA issued a black box warning that long-term use of metoclopramide has been linked to the development of tardive dyskinesia.[111]

Erythromycin (Ery-Tab)

Macrolide antibiotic that duplicates the action of motilin, which is responsible for the migrating motor complex activity. Binds to and activates motilin receptors. IV administration of this drug enhances the emptying rate of both liquids and solids. Effect can be seen with PO erythromycin. Substitution of the enteric-coated form may be tolerated better by the patient.

Metoclopramide (Reglan)

Dopamine antagonist that stimulates acetylcholine release in the myenteric plexus. Acts centrally on chemoreceptor triggers in the floor of the fourth ventricle, which provides important antiemetic activity; side effects and tachyphylaxis are problems.

Antidepressant, Tetracyclic

Desipramine (Norpramin)

These agents have been suggested to act by inhibiting reuptake of noradrenaline at synapses in central descending pain modulating pathways located in the brainstem and spinal cord.

Synthetic Adrenocortical Steroids

Class Summary

Florinef is used in severely symptomatic orthostatic hypotension. Use if salt tablets and pressure stockings fail to alleviate hypotension.

Fludrocortisone acetate (Florinef)

Used to increase standing blood pressure. Acts to increase sodium retention and expand plasma volume.

Cholinergic Agent

Bethanechol hydrochloride

Used for selective stimulation of the bladder to produce contraction to initiate micturition and empty the bladder. Found to be most useful in patients who have bladder hypocontractility, provided they have functional and coordinated sphincters. Rarely used due to difficulty in timing effect and because of gastrointestinal stimulation.

Laxative, Bowel Evacuant

Polyethylene glycol (PEG) solution (MiraLax, GlycoLax)

For treatment of occasional constipation. In theory, less risk of dehydration or electrolyte imbalance with isotonic polyethylene glycol compared with hypertonic sugar solutions. Laxative effect generated because polyethylene glycol is not absorbed and continues to hold water by osmotic action through small bowel and colon, resulting in mechanical cleansing.

 

Questions & Answers

Overview

What is diabetic neuropathy?

What are the signs and symptoms of diabetic neuropathy?

What should the physical exam of diabetic neuropathy include?

What is the modified Thomas classification system for diabetic neuropathy?

How is distal symmetrical sensorimotor polyneuropathy defined?

How common is pure autonomic diabetic neuropathy?

What are asymmetrical diabetic neuropathies?

How is diabetic polyneuropathy staged?

Which lab tests may be helpful in the diagnosis of diabetic neuropathy?

Which imaging modalities may be considered for the diagnosis of diabetic neuropathy?

What are the key components of diabetic neuropathy management?

Which autonomic dysfunctions must be managed in patients with diabetic neuropathy?

What are the surgical options for diabetic neuropathy?

How is diabetic neuropathy defined?

What is the frequency of diabetic neuropathy?

What are secondary complications of diabetic neuropathy?

What are the manifestations of diabetic neuropathy?

What is the role of electrophysiologic testing in the evaluation of diabetic neuropathy?

How is diabetic neuropathy managed?

What are the treatment options for diabetic neuropathy?

How are peripheral neurons categorized in diabetic neuropathy?

What is the anatomy of motor neurons in diabetic neuropathy?

What is the anatomy of sensory neurons in diabetic neuropathy?

What is the anatomy of autonomic neurons in diabetic neuropathy?

What are the subdivision of sensory neurons in diabetic neuropathy?

What are the risk factors for the development of diabetic neuropathy?

What is the role of hyperglycemia in the pathophysiology of diabetic neuropathy?

What is the role of advanced glycation end products (AGEs) in the pathophysiology of diabetic neuropathy?

What is the role of oxidative stress in the pathophysiology of diabetic neuropathy?

What are contributing factors to the development of focal or asymmetrical diabetic neuropathy syndromes?

What are the risk factors associated with severe symptoms of diabetic neuropathy?

How do symptoms of diabetic neuropathy develop?

What is the most common etiologic mechanism of diabetic neuropathy?

What is the association between impaired glucose tolerance and diabetic peripheral neuropathy?

What are the roles of poor glycemic control, nerve conduction loss, and lipid metabolism changes in the etiology of diabetic peripheral neuropathy?

What is the association between variability in fasting plasma glucose and diabetic peripheral neuropathy?

What is the role of obstructive sleep apnea (OSA) in the etiology of diabetic neuropathy?

What is the odds ratio for peripheral neuropathy in patients with type 2 diabetes versus those with type 1?

What is the prevalence of diabetic neuropathy in the US?

Why is there variability in US prevalence data for diabetic neuropathy?

What is the global prevalence of diabetic neuropathy?

What are the racial predilections for diabetic neuropathy?

How does the prevalence of diabetic neuropathy vary by sex?

How does the prevalence of diabetic neuropathy vary by age?

What is the prognosis of untreated diabetic neuropathy?

What are the limitations of diabetic neuropathy treatments?

What is the mortality rate for diabetic neuropathy?

How does tertiary care affect the outcomes of diabetic neuropathy?

What is the role of diet and nutrition in the management of diabetic neuropathy?

What activity modifications are needed for patients with diabetic neuropathy?

What information about diabetic neuropathy should patients be given?

What foot protection and care instructions should patients with diabetic neuropathy receive?

What are the ophthalmologic and renal conditions associated with diabetic neuropathy?

Where should patient education for diabetic neuropathy be given?

What is diabetic neuropathy?

How does diabetic neuropathy occur?

What are the symptoms of diabetic neuropathy?

How is the pain of diabetic neuropathy characterized?

How is diabetic neuropathy prevented?

How is diabetic neuropathy treated?

What are the self-care measures for diabetic neuropathy?

What is the duration of diabetic neuropathy symptoms?

Presentation

What should be the focus of history for diabetic neuropathy?

What are the sensory symptoms of diabetic neuropathy?

What are the motor symptoms of diabetic neuropathy?

What is the most common presentation of diabetic neuropathy?

What are the autonomic symptoms of diabetic neuropathy?

What are the GI symptoms of diabetic neuropathy?

What are the cardiovascular symptoms of diabetic neuropathy?

What are the symptoms of bladder neuropathy in patients with diabetes?

What are the sudomotor symptoms of diabetic neuropathy?

What is included in the physical exam of patients with diabetic neuropathy?

What is the role of pinprick testing in the assessment of diabetic neuropathy?

How is vibratory sense in the feet assessed in diabetic neuropathy?

How are deep tendon reflexes assessed in diabetic neuropathy?

What is the focus of skin exam in diabetic neuropathy?

What does a finding of paresthesias suggest in the assessment of diabetic neuropathy?

How is cranial nerve testing performed in patients with diabetic neuropathy?

What should be included in an annual screening for diabetic neuropathy?

When is specialized autonomic testing indicated in the assessment of diabetic neuropathy?

How is blood pressure measured in the assessment of diabetic neuropathy?

What are the classification systems for diabetic neuropathy?

What is the Thomas system for classification of diabetic neuropathy?

What are the broad classifications used for diabetic neuropathy?

What are the criteria used to define distal symmetrical sensorimotor diabetic polyneuropathy?

What is chronic symmetrical diabetic neuropathy?

What is the progression of symptoms for chronic symmetrical diabetic neuropathy?

What is small-fiber diabetic neuropathy?

What are some manifestations of autonomic diabetic neuropathy?

What is diabetic neuropathic cachexia?

What are the subtypes of asymmetrical diabetic neuropathy?

How are asymmetrical diabetic differentiated from distal diabetic neuropathy?

What is cranial diabetic mononeuropathy?

What are manifestations of facial diabetic neuropathy?

What are manifestations of anterior ischemic optic diabetic neuropathy?

What are somatic diabetic mononeuropathies?

What are the signs and symptoms of diabetic thoracic radiculoneuropathy?

Where in the body does diabetic radiculoplexus neuropathy occur?

What are the symptoms of diabetic radiculoplexus neuropathy?

How is the severity of diabetic neuropathy assessed?

How is diabetic neuropathy staged?

DDX

What is required to establish the diagnosis of diabetic neuropathy?

What are the differential diagnoses for cranial diabetic mononeuropathy?

What are the differential diagnoses for thoracoabdominal diabetic neuropathy?

What are the differential diagnoses for diabetic lumbosacral radiculoplexopathy?

What are the differential diagnoses for peripheral diabetic neuropathy?

What are the differential diagnoses for cardiovascular autonomic neuropathy?

What are the differential diagnoses for GI diabetic neuropathy?

What are the differential diagnoses for bladder dysfunction in diabetic neuropathy?

What are the differential diagnoses for diabetic mononeuropathy?

What are the differential diagnoses for Diabetic Neuropathy?

Workup

Which lab tests are used to screen for diabetic neuropathy?

What is the role of imaging studies in the diagnosis of diabetic neuropathy?

What is the role of electrophysiologic testing in the diagnosis of diabetic neuropathy?

What is the accuracy of screening tools used for diabetic neuropathy?

What is the role of hemoglobin A1c measurement and fasting plasma glucose testing in the diagnosis of diabetic neuropathy?

Which tests are used to exclude common causes of neuropathy other than diabetes?

What is the role of nerve conduction studies (NCS) and electromyography (EMG) in the diagnosis of diabetic neuropathy?

What is the role of nerve conduction velocity (NCV) studies in the diagnosis of diabetic neuropathy?

What is the role of needle electromyography (EMG) in the diagnosis of diabetic neuropathy?

Which nerve conduction study findings are characteristic of diabetic neuropathy?

Which findings on electromyographic samplings are characteristic of diabetic neuropathy?

How are electrophysiologic studies used for the diagnosis of diabetic neuropathy?

What is the role of MRI and CT scanning in the diagnosis of diabetic neuropathy?

What is the role of nuclear imaging in the diagnosis of diabetic neuropathy?

What is the role of Doppler imaging in the diagnosis of diabetic neuropathy?

What is the role of microdialysis in the diagnosis of diabetic neuropathy?

What is the role of electrocardiography in the diagnosis of diabetic neuropathy?

What is the role of nerve biopsy in the diagnosis of diabetic neuropathy?

What is the role of skin biopsy in the diagnosis of diabetic neuropathy?

Why are biopsies rarely recommended for the diagnosis of diabetic neuropathy?

Which diagnostic approaches for diabetic neuropathy are investigational?

Treatment

When should the management of diabetic neuropathy begin?

What complications are at increased risk with diabetic peripheral neuropathy?

What is included in the follow-up of patients with peripheral diabetic neuropathy?

What is the role of a primary care physicians in the treatment of diabetic neuropathy?

What is the role of glycemic control in the treatment of diabetic neuropathy?

Which medications are used in the treatment of diabetic neuropathic pain?

What is the role of gabapentin in the treatment of diabetic neuropathy?

What are the AAN/AANEM/AAPMR treatment guidelines for painful diabetic neuropathy (PDN)?

What are the AAN/AANEM/AAPMR guidelines for topical treatment used for painful diabetic neuropathy (PDN)?

What are the advantages and disadvantages of administering off-label medications to treat diabetic neuropathic?

What is the role of duloxetine in the treatment of diabetic neuropathy?

What are the differences in efficacy between gabapentin and tricyclic antidepressants for the treatment of diabetic neuropathic pain?

Which medications are used to control diabetic neuropathic pain during pregnancy?

Which medications are used to treat gastroparesis in diabetic neuropathy?

What is the role of dietary supplements in the treatment of diabetic neuropathy?

What is the role of aldose reductase inhibitors in the treatment of diabetic neuropathy?

What is the role of alpha-lipoic acid in the treatment of diabetic neuropathy?

What is the role of actovegin in the treatment of diabetic neuropathy?

What is the role of spinal cord stimulator implants in the treatment of diabetic neuropathy?

How is erectile dysfunction due to diabetic neuropathy treated?

How is symptomatic orthostatic hypotension due to diabetic neuropathy treated?

How is gustatory sweating in diabetic neuropathy treated?

When is surgery indicated in the treatment of diabetic neuropathy?

What is the role of jejunostomy in the treatment of diabetic neuropathy?

When is penile prosthesis indicated in the treatment of diabetic neuropathy?

How are feet complications of diabetic neuropathy treated?

What are the benefits of pancreatic transplantation for treatment of diabetic neuropathy?

What is the role of physical therapy in the treatment of diabetic neuropathy?

What is the role of transcutaneous electrical nerve stimulation (TENS) in the treatment of diabetic neuropathy?

When is physical therapy indicated in the treatment of foot ulcers due to diabetic neuropathy?

What are some therapies used to improve balance in patients with diabetic neuropathy?

When is occupational therapy indicated in the treatment of diabetic neuropathy?

When is speech therapy indicated in the treatment of diabetic neuropathy?

What is the role of recreational therapy in the treatment of diabetic neuropathy?

What are possible complications of peripheral diabetic neuropathy?

What are possible complications of autonomic diabetic neuropathy?

What is the role of an endocrinologist in the management of diabetic neuropathy?

When is a neurology consultation indicated in the management of diabetic neuropathy?

What are the benefits of physical medicine and rehabilitation in the management of diabetic neuropathy?

When are specialist consultations needed in the management of diabetic neuropathy?

What is included in the long-term monitoring of diabetic neuropathy?

Medications

Which medications are used in the treatment of diabetic neuropathy?

Which medications in the drug class Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) are used in the treatment of Diabetic Neuropathy?

Which medications in the drug class Analgesic, Topical are used in the treatment of Diabetic Neuropathy?

Which medications in the drug class Anticonvulsant are used in the treatment of Diabetic Neuropathy?

Which medications in the drug class Antidepressant, Tricyclic are used in the treatment of Diabetic Neuropathy?

Which medications in the drug class Antidepressant, Selective Serotonin/norepinephrine Reuptake Inhibitor (SSNRI) are used in the treatment of Diabetic Neuropathy?

Which medications in the drug class Antidepressant, Serotonin Reuptake Inhibitor are used in the treatment of Diabetic Neuropathy?

Which medications in the drug class Antiarrhythmic Agent, Class I-b are used in the treatment of Diabetic Neuropathy?

Which medications in the drug class Prokinetic Agents are used in the treatment of Diabetic Neuropathy?

Which medications in the drug class Antidepressant, Tetracyclic are used in the treatment of Diabetic Neuropathy?

Which medications in the drug class Synthetic Adrenocortical Steroids are used in the treatment of Diabetic Neuropathy?

Which medications in the drug class Cholinergic Agent are used in the treatment of Diabetic Neuropathy?

Which medications in the drug class Laxative, Bowel Evacuant are used in the treatment of Diabetic Neuropathy?