Type 2 Diabetes Mellitus Treatment & Management

The goals in caring for patients with diabetes mellitus are to eliminate symptoms and prevent, or at least slow, the development of complications. Microvascular (ie, eye and kidney disease) risk reduction is accomplished through control of glycemia and blood pressure (BP); macrovascular (ie, coronary, cerebrovascular, peripheral vascular) risk reduction, through control of lipids and hypertension, smoking cessation, and aspirin therapy; and metabolic and neurologic risk reduction, through control of glycemia.

Diabetes care requires appropriate goal setting, dietary and exercise modifications, medications, appropriate self-monitoring of blood glucose (SMBG), regular monitoring for complications, and laboratory assessment.

Ideally, blood glucose should be maintained at near-normal levels (preprandial levels of 90-130 mg/dL and hemoglobin A1C [HbA1c] levels < 7%). However, focus on glucose alone does not provide adequate treatment for patients with diabetes mellitus. Treatment involves multiple goals (ie, glycemia, lipids, BP) and is best provided by a multidisciplinary team of health professionals with expertise in diabetes.

With each healthcare system encounter, patients with diabetes should be educated about and encouraged to follow an appropriate treatment plan. Adherence to diet and exercise should continue to be stressed throughout treatment, because these lifestyle measures can have a large effect on the degree of diabetic control that patients can achieve. A study by Thaning et al revealed normal endothelial function and functional sympatholysis in patients with diabetes.^[76] Declining effects were more a function of aging.

A study by Morrison et al found that more frequent visits with a primary care provider (every 2 wk) led to markedly rapid reductions in serum glucose, HbA1c, and LDL cholesterol levels. However, how such a strategy can work globally remains a challenge due to available resources and economic restrictions.^[77]

Providers must ensure that the care for each patient with diabetes includes all necessary laboratory tests, examinations (eg, foot and neurologic examinations), and referrals to specialists (eg, ophthalmologist, podiatrist).

The care of patients with type 2 diabetes mellitus has been profoundly shaped by the results of the United Kingdom Prospective Diabetes Study (UKPDS). This landmark study confirmed the importance of glycemic control in reducing the risk for microvascular complications and refuted previous data suggesting that treatment with sulfonylureas or insulin increased the risk of macrovascular disease. Major findings of the UKPDS are displayed in the images below.

Significant implications include the following:

• Microvascular complications (predominantly indicated by the need for laser photocoagulation of retinal lesions) are reduced by 25% when median hemoglobin A1c (HbA1c) is 7%, compared with 7.9%.
• A continuous relationship exists between glycemia and microvascular complications, with a 35% reduction in risk for each 1% decrement in HbA1c. A glycemic threshold (above the upper limit of normal for HbA1c) below which risk for microvascular disease is eliminated does not appear to exist.
• Glycemic control has minimal effect on macrovascular disease risk. Excess macrovascular risk appears to be related to conventional risk factors such as dyslipidemia and hypertension.
• Sulfonylureas and insulin therapy do not increase macrovascular disease risk.^[38]
• Metformin reduces macrovascular risk in patients who are obese.^[78]
• Roussel et al studied the expanded use of metformin in groups of patients with diabetes previously considered high risk for possible drug-related adverse outcome and found a decrease in mortality in these patients.^[79]
• Vigorous BP control reduces microvascular and macrovascular events.^[80] Beta-blockers and angiotensin-converting enzyme (ACE) inhibitors appear to be equally effective.
• In a study by Pergola et al, bardoxolone methyl, an oral antioxidant inflammatory modulator, was shown to improve estimated GFR in patients with advanced chronic kidney disease and type 2 diabetes mellitus at 24 weeks, and the improvement persisted at 52 weeks.^[81]
• High plasma fatty acids cause both microvascular and metabolic insulin resistance. This can be prevented or attenuated by using salsalate, an anti-inflammatory agent.^[82]

Sulfonylureas

Sulfonylureas are insulin secretagogues that stimulate insulin release from pancreatic beta cells and probably have the greatest efficacy for glycemic lowering of any of the oral agents.

One study exonerates the sulfonylurea group of oral agents as the chief cause of cardiovascular death in those admitted with acute myocardial infarction. However, even though sulfonylureas were safer in general, within the group, use of glyburide was associated with highest mortality (7.5%) compared with other sulfonylureas such as gliclazide or glimepiride (2.7%).^[83] This raises an important concern about whether the use of glyburide should be avoided.

Meglitinides

Meglitinides are much more short-acting insulin secretagogues than sulfonylureas, with preprandial dosing potentially achieving more physiologic insulin release and less risk for hypoglycemia. Their glycemic efficacy is possibly less than sulfonylureas.

Biguanides

Biguanides are old agents that reduce hepatic glucose production and may have a minor effect on glucose utilization in the periphery. Insulin must be present for biguanides to work. Phenformin was taken off the market in the United States in the 1970s because of its risk of causing lactic acidosis and associated mortality (rate of approximately 50%). Metformin has proved effective and safe.^[84]

A nested case-control analysis found that, as with other oral antidiabetic drugs, lactic acidosis during metformin use is very rare and is associated with concurrent comorbidity; moreover, hypoglycemic episodes are substantially less common among patients taking metformin than they are among those taking sulfonylureas.^[85]

In addition, metformin is the only oral diabetes drug that reliably facilitates modest weight loss. In the UKPDS, it was found to be successful at reducing macrovascular disease endpoints in patients who were obese.^[86] The results with concomitant sulfonylureas in a heterogeneous population were conflicting,^[87] but overall, this drug probably improves macrovascular risk.

Kooy et al found improvements in body weight, glycemic control, and insulin requirements when metformin was added to insulin in patients with type 2 diabetes mellitus. No improvement of an aggregate of microvascular and macrovascular morbidity and mortality was observed; however, risk reduction of macrovascular disease was evident after a follow-up period of 4.3 years. These sustained beneficial effects indicated that, unless contraindicated, metformin treatment should be continued after the introduction of insulin in patients with type 2 diabetes mellitus.^[88]

Pradhan et al did not find an association between improving glycemic control with metformin or insulin and reducing inflammatory biomarker levels in patients with recent-onset type 2 diabetes mellitus.^[89] Patients were randomized to 1 of 4 groups: placebo, placebo plus insulin glargine, metformin only, and metformin and insulin glargine. HbA1c and glucose levels were reduced with active treatment compared with placebo, but no difference in levels of the inflammatory biomarker high-sensitivity C-reactive protein (hsCRP) was shown between study participants who received insulin or metformin and those who did not.

A retrospective nationwide cohort study found that metformin is associated with a low risk of mortality in patients who have diabetes and experience heart failure compared with treatment that includes a sulfonylurea or insulin.^[90]

A study by Gross et al found no difference in benefit between drug classes in patients already on metformin and sulfonylurea. The patient's clinical circumstances must guide selection.^[91]

Alpha-glucosidase inhibitors

These agents delay sugar absorption and help prevent postprandial glucose surges. Alpha-glucosidase inhibitors prolong the absorption of carbohydrates, but their induction of flatulence greatly limits their use. They should be titrated slowly to reduce GI intolerance.

Thiazolidinediones (glitazones)

Glitazones require the presence of insulin to work. They generally decrease triglycerides and increase HDL-C, but they increase LDL-C (perhaps large buoyant LDL, which may be less atherogenic). While these drugs have many desirable effects on inflammation and the vasculature, edema and weight gain may be problematic adverse effects, especially when glitazones are administered with insulin or insulin secretagogues. These effects may induce or worsen heart failure in patients with left ventricular compromise and occasionally in patients with normal left ventricular function. These agents have not been tested in patients with New York Heart Association class III or IV heart failure. A recognized possible side effect of these agents is macular edema. Animal work suggests that concomitant therapy with the diuretic amiloride may reduce fluid retention related to glitazone therapy.

The PROspective pioglitAzone Clinical Trial In macroVascular Events (PROactive) trial assessed the effect of pioglitazone titrated to 45 mg/d versus placebo, added to existing diabetes therapy on macrovascular outcomes. No statistically significant difference was noted between the 2 groups at 3 years. A later-developed main secondary endpoint (all-cause mortality, nonfatal myocardial infarction, and stroke) not mentioned in the original study design was reduced 16%.^[92] Treated patients gained 4 kg on average and had a much higher rate of heart failure and edema than patients treated with placebo. The author views this study as primarily a confirmation of concerns over weight gain, edema, and heart failure with these drugs and thinks their potential antiatherosclerotic effects are still unproven.

Use of pioglitazone for more than 2 years is weakly associated with an increased bladder cancer risk.^{[93, 94]} Adverse event reporting system analysis is consistent with an association between pioglitazone and bladder cancer.^[95] Constant surveillance and vigilance is needed.Ninety-five percent of these cases were detected in early stage. Charpentier et al concluded that early triple therapy in patients who are not responding to dual therapy is beneficial, decreasing HbA1c, as well as improving fasting plasma glucose levels and other surrogate markers.^[96]

In this study, patients (n=299) with type 2 diabetes mellitus uncontrolled by dual combination therapy (metformin and a sulfonylurea or a glinide) were randomly assigned to receive add-on therapy with either pioglitazone 30 mg/d or placebo.^[96] Among patients with a baseline HbA1c level of less than 8.5%, 44.4% in the pioglitazone group achieved an HbA1c level of less than 7% after 7 months, compared with only 4.9% of patients in the placebo group. In patients with a baseline HbA1c level of 8.5% or greater, 13% of those in the pioglitazone group achieved an HbA1c level of less than 7%, while no patients in the placebo group saw the same reduction.

In a study by DeFronzo et al, pioglitazone was found to reduce the progression to frank diabetes by 72% in patients with impaired glucose tolerance.^[97] However, this was associated with significant edema and weight gain.

A study indicates that in women with type 2 diabetes, long-term (ie, 1 y or longer) use of glitazones doubles the risk of fracture.^[98] In this investigation, glitazones did not significantly increase fracture risk among men with type 2 diabetes. Risk of fracture has also since been reported for men.

The US Food and Drug Administration issued an alert on May 21, 2007 to patients and health care professionals of rosiglitazone potentially causing an increased risk of myocardial infarction (MI) and heart-related deaths following the online publication of a meta-analysis. Rosiglitazone is an antidiabetic agent (thiazolidinedione derivative) that improves glycemic control by improving insulin sensitivity. The drug is highly selective and a potent agonist for peroxisome proliferator-activated receptor-gamma (PPAR-gamma).

In a large-scale trial, the RECORD (Rosiglitazone Evaluated for Cardiac Outcomes and Regulation of Glycaemia in Diabetes) study, cardiovascular outcomes were assessed after adding rosiglitazone to metformin or sulfonylurea regimens for type 2 diabetes mellitus.^[98] The study was a multicenter, open-label trial that included 4447 patients with mean HbA1c of 7.9%. Follow-up of the 2 drug combinations took place over 5-7 years. No difference was observed between the 2 groups for cardiovascular death, myocardial infarction, or stroke.

In the study, 61 patients who received rosiglitazone experienced heart failure that caused either hospital admission or death, compared with 29 patients in the active control group (hazard ratio [HR] 2.10, 1.35-3.27, risk difference per 1000 person-years 2.6, 1.1-4.1). Noncardiovascular adverse effects included increased upper and distal lower limb fracture rates, particularly in women. At 5 years, mean HbA1c was lower in the rosiglitazone group compared with the active control group. The investigators concluded that the use of rosiglitazone for type 2 diabetes mellitus increases the risk of heart failure. The study’s results also indicated that the risk for select fractures, particularly in women, is increased as well.

In the Canadian Normoglycemia Outcome and Evaluation (CANOE) trial, despite preventing incident diabetes, low-dose rosiglitazone/metformin did not modify the natural history of worsening insulin resistance and beta cell function.^[99]

Glitazones act as insulin sensitizers. These drugs are selective agonists for peroxisome proliferator-activated receptor-gamma (PPAR-gamma). Activation of PPAR-gamma receptors regulates insulin-responsive gene transcription involved in glucose production, transport, and utilization, thereby reducing blood glucose concentrations and hyperinsulinemia. They must be taken for 12-16 weeks to achieve maximal effect. They must be taken for 12-16 weeks to achieve maximal effect. These agents are used as monotherapy or with sulfonylurea, metformin, meglitinide, DPP-IV inhibitors, exenatide or insulin. They are the only antidiabetes agents that have been shown to slow progression of diabetes (particularly in early disease) presumably by preserving beta-cell function.

Older men with impaired fasting glucose and diabetes have accelerated muscle loss, except when diabetes is treated with insulin sensitizers.^[100]

A study by Phung et al investigated oral agents used for prevention of type 2 diabetes and found that thiazolidinediones resulted in a greater risk reduction than biguanides. Sulfonylureas and glinides had no benefit.^[101]

Incretin mimetics

The incretin-mimetic agent exenatide mimics the endogenous incretin, glucagonlike peptide-1 (GLP-1); it stimulates glucose-dependent insulin release; it reduces glucagon; and it slows gastric emptying.

Studies have used exenatide in addition to metformin and/or a sulfonylurea. Patients may attain modest weight loss. Animal data suggest that this drug prevents beta-cell apoptosis and, in time, may restore beta-cell mass. This latter property, if proven in humans, would have tremendous therapeutic potential.

Exenatide has greater ease of titration (only 2 possible doses, with most patients progressing to the higher dose) than does insulin. However, exenatide is more expensive than high-dose glitazone therapy and requires twice-daily injections. A long-acting formulation (Bydureon) that is given once weekly was approved by the US Food and Drug Administration (FDA) in January 2012 and has been found to provide significantly greater improvement in glycemic control than does the twice-daily formulation.^[102] This observation was confirmed in the DURATION-5 study (Diabetes therapy Utilization: Researching changes in A1C, weight and other factors Through Intervention with exenatide ONce weekly) study.^[103]

A comparison by Bunck et al of 1 year's therapy with either exenatide or insulin glargine in metformin-treated patients with type 2 diabetes found that exenatide provided significantly greater improvement in beta-cell function. Reduction in HbA1c was similar with the 2 drugs. Beta-cell function and glycemic control returned to pretreatment values following discontinuation of exenatide or insulin glargine, suggesting that long-term treatment is required to maintain the beneficial effects of these drugs.^[104]

The addition of exenatide in patients receiving insulin glargine as basal insulin helps improve glycemic control without risk of increased hypoglycemia or weight gain. This benefit, however, is accompanied by a significant increase in adverse events such as nausea, diarrhea, vomiting, and headache.^[105] Less nausea was observed with the once-weekly exenatide formulation compared with the twice-daily preparation.^[103]

Dipeptidyl peptidase IV inhibitors

The dipeptidyl peptidase IV (DPP-4) inhibitor sitagliptin gained FDA approval in October 2006. These agents prolong action of incretin hormones. DPP-4 degrades numerous biologically active peptides, including the endogenous incretins GLP-1 and GIP. Sitagliptin can be used as a monotherapy or in combination with metformin or a glitazone. It is given once daily and is weight neutral. The FDA approved saxagliptin in July 2009 and linagliptin in May 2011. Another DPP-4 inhibitor, vildagliptin, is currently under review at the FDA. One year of treatment with vildagliptin significantly increased beta cell secretory capacity; however, this was not maintained after a wash-out period, indicating that increased secretory capacity did not have a disease-modifying effect on the beta cell function or mass.^[106]

Aschner et al conducted a study comparing the efficacy and safety of monotherapy with sitagliptin with those of monotherapy with metformin in 1050 treatment-naive patients with type 2 diabetes and HbA1c of 6.5-9%. Participants were randomized to treatment with sitagliptin (100 mg PO qd) or metformin (1000 mg PO bid) for 24 weeks. No statistical differences were found between sitagliptin and metformin for decreased HbA1c and fasting glucose levels from baseline. Gastrointestinal adverse effects were lower with sitagliptin (11.6%) than with metformin (20.7%), with significantly decreased incidences of diarrhea (3.6% vs 10.9%, respectively) and nausea (1.1% vs 3.1%, respectively) in the sitagliptin patients.^[107]

In a study by Vilsboll et al, improved glycemic control was observed when sitagliptin was added to stable-dose insulin therapy (with or without concomitant metformin administration) in patients with type 2 diabetes mellitus. The addition of sitagliptin produced a greater reduction in fasting plasma glucose (by 15 mg/dL [0.8 mmol/L]) and 2-hour postprandial glucose (by 36.1 mg/dL [2 mmol/L]) than did placebo. Moreover, sitagliptin reduced HbA1c by 0.6%, while no reduction was seen with placebo. The investigators also found that 13% of patients attained an HbA1c level of less than 7% with sitagliptin, compared with 5% with placebo.^[108]

A study by Pérez-Monteverde et al found that a combination of sitagliptin and metformin was associated with improved glycemic control and less weight gain when compared with pioglitazone in the treatment of patients with type 2 diabetes mellitus.^[109]

Adding linagliptin in patients with type 2 diabetes mellitus that was inadequately controlled by metformin and sulfonylurea combination improves glycemic control. Because it has predominantly nonrenal excretion and is a clinically nonrelevant substrate for cytochrome 450 isoenzymes, this drug is a good choice, with low risk of drug-drug interaction and safe use in cases with renal insufficiency.^[110]

A study by Willemen et al determined that upper respiratory tract infections have been increasingly reported among users of DPP-4 inhibitors compared with users of other antidiabetic drugs.^[111] However, further research is needed to evaluate the scope and the underlying mechanisms.

Treatment with DPP-4 inhibitors could reduce risk for bone fractures.^[112]

Insulin

Ultimately, many patients with type 2 diabetes mellitus become markedly insulinopenic. The only therapy that corrects this defect is insulin. Because most patients are insulin resistant, small changes in insulin dosage may make no difference in glycemia in some patients. Furthermore, because insulin resistance is variable from patient to patient, therapy must be individualized in each patient.

A study by de la Pena et al found that although overall insulin exposure and effects of 500 U/mL of insulin are similar to 100 U/mL of insulin, peak concentration was significantly lower at 500 U/mL of insulin, and the effect after the peak was prolonged; areas under the curve were similar for both doses. This observation should help guide therapy.^[113]

A range of insulin preparations, individual and premixed, is currently available. The AHRQ has reviewed the use of premixed insulin analogues in patients with type 2 diabetes mellitus; conclusions for which the strength of evidence was high are as follows^[114] :

• For lowering postprandial glucose, premixed insulin analogues are more effective than either long-acting insulin analogues alone or premixed NPH/regular human insulin 70/30.
• For lowering HbA1c, premixed insulin analogues are as effective as premixed NPH/regular human insulin 70/30 and more effective than long-acting insulin analogues.
• The frequency of hypoglycemia reported with premixed insulin analogues is similar to that with premixed human insulin and higher than that with oral antidiabetic agents.

On July 1, 2009, the FDA issued an early communication to health care practitioners regarding 4 recently published observational studies that described the possible association of insulin glargine (Lantus), a long-acting human insulin analogue approved for once-daily dosing, with an increased risk of cancer.^[115]

The observational studies evaluated large patient databases, and all reported some association between insulin glargine and other insulin products with various types of cancer. The duration of the observational studies was shorter than that considered to be necessary to evaluate for drug-related cancers. Additionally, findings were inconsistent within and across the studies, and patient characteristics differed across treatment groups. These issues raise further questions about the risk that actually exists, and therefore warrants further evaluation.

In a study by Suissa et al, insulin glargine use was not associated with an increased risk of breast cancer during the first 5 years of use. The risk tended to increase after 5 years, significantly so for the women who had taken insulin before starting glargine.^[116] Furthermore, a study by Johnson et al found that patients receiving insulin glargine had the same incidence rate for all cancers as those not receiving insulin glargine. Overall, no increase in breast cancer rates was associated with insulin glargine use, although patients who used only insulin glargine had a higher rate of cancer than those who used another type of insulin. This was attributed to allocation bias and differences in baseline characteristics.^[117]

A study by Steansdottir showed that different drug regimens used to accomplish intensified glycemic control did not alter the risk of cancer in patients with diabetes.^[118] This study differs from previous studies where metformin use was associated with lower cancer risk. For example, Ruiter et al found a link between cumulative exposure to metformin and lower risk of specific cancers and cancers in general, compared with cumulative exposure to sulfonylurea derivatives.^[119] Whether this indicates a decreased risk of cancer associated with metformin or an increased risk associated with sulfonylurea use remains to be seen.

The FDA states that patients should not stop taking their insulin without consulting their physician. An ongoing review by the FDA will continue to update the medical community and consumers with additional information as it emerges. Statements from the American Diabetes Association and the European Association for the Study of Diabetes called the findings conflicting and inconclusive and cautioned against overreaction.

A study by Zinman et al found that insulin degludec, a new basal insulin that forms soluble multihexamer assemblies after subcutaneous injection, provides comparable glycemic control to insulin glargine without additional adverse effects.^[120] A reduced dosing frequency may be possible because of its ultra long–action profile. Careful study is needed when making a decision regarding reduced dosing frequency.

The first inhaled insulin (Exubera) was approved by the FDA in January 2006 as a rapid-acting prandial insulin. It did not produce better glycemic control than did conventionally injected insulins and required a mildly cumbersome device, skill to deliver an accurate dose (up to a few minutes to deliver 1 dose), and pulmonary function monitoring due to concerns about lung toxicity over time. Exubera was withdrawn from the market in October 2007; this was done not because of safety concerns but because too few patients were using the product for its continued sale to be economically feasible.

A standardized protocol can be effective in transitioning patients who have diabetes and acute coronary syndrome to subcutaneous insulin once oral feeding has resumed. This is based on insulin requirement during the previous 12 hours. Half the amount is given as basal insulin, and the remainder is given as prandial insulin.^[121]

Amylin analogs

Amylin analogs mimic endogenous amylin effects by delaying gastric emptying, decreasing postprandial glucagon release, and modulating appetite.^[122]

Leptin

Metreleptin administration in obese patients with type 2 diabetes did not alter body weight or concentration of circulating markers of inflammation but marginally reduced HbA1c levels. Leptin tolerance may be related to endoplasmic reticulum stress and saturable nature of leptin receptor.^[123]

Bile acid sequestrant

Colesevelam is FDA-approved as an adjunctive therapy to improve glycemic control. Colesevelam is a relatively safe addition to the menu of choices available to reduce LDL cholesterol in patients with prediabetes. It should be avoided in patients with hypertriglyceridemia (a rule that applies to bile acid sequestrants in general). It has a favorable but insignificant impact on fasting plasma glucose and HbA1c levels.^[124]

One study examined initial combination therapy of metformin and colesevelam to determine achievement of glycemic and lipid goals in early type 2 diabetes. The study suggested that the A1c reduction is clinically irrelevant even if statistically significant. No data show that a 0.3% reduction of A1c has a better outcome than a 0.2% reduction of aA1c. However, LDL goals were achieved in more patients, but it is not known if that correlates with any significantly different outcomes in these patients.^[125]

Glucokinase activators

In a phase 1b randomized, double-blind, placebo-controlled crossover trial, a novel glucokinase activator, piragliatin, was shown to improve beta cell function; it has the potential for use as a therapeutic strategy in patients with type 2 diabetes mellitus.^[126]

In a study by Meininger et al, glucokinase activator MK-0941 administration in patients with type 2 diabetes mellitus led to unsustainable but significant improvements in postmeal glucose control, without significant effect on fasting glucose. However, significant increases were noted in the incidence of hypoglycemia, elevation of blood pressure, and plasma triglyceride levels.^[127]

Fibroblast growth factor

In patients with critical limb ischaemia, nonviral 1 fibroblast growth factor (NV1FGF) offered no protection against the risk of amputations and no reduction in death rate.^[128]

At the time of diagnosis, management of hyperglycemia in most patients with type 2 diabetes mellitus should begin with lifestyle modification (diet and activity) implemented by health care professionals, in combination with metformin, according to a consensus recommendation by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD).^[129]

Advantages of metformin include its efficacy, absence of weight gain or hypoglycemia, generally low level of side effects, high level of patient acceptance, and relatively low cost. The dose of metformin is titrated over 1–2 months to at least 2000 mg/d administered in divided doses (during or after meals to reduce gastrointestinal side effects). If the patient fails to achieve or sustain glycemic goals within 2-3 months, another medication should be added—generally, either insulin or a sulfonylurea (see Medication). Insulin rather than metformin may be used initially in patients who present with weight loss or severe manifestations of hyperglycemia. Exercise increases metformin levels and interfere with its glucose lowering effect.^[130]

The Agency for Healthcare Research and Quality (AHRQ) reviewed the published evidence (which came from short-term studies but was applicable to long-term use) regarding the comparative effectiveness of oral diabetes medications; the agency found little evidence to support predictions as to whether a particular medication is more likely to be effective in a given patient subgroup or to cause adverse effects in a particular patient.

The AHRQ concluded that, when used as a monotherapy, most oral diabetes medications (with the exception of the less-effective nateglinide and alpha-glucosidase inhibitors) produce similar reductions in HbA1c and that older medications (eg, metformin, second-generation sulfonylureas) can reasonably be used before newer ones (eg, glitazones, meglitinides), especially when cost is a factor.^[131]

Based on the results of the UKPDS and safety record, patients who are obese (120% ideal body weight) should be started on metformin initially. Patients who are markedly symptomatic may be treated with an insulin secretagogue initially to rapidly alleviate symptoms and then perhaps switched to other agents. Patients with near-normal weight may be treated with sulfonylureas or metformin initially. Short-acting insulin secretagogues (eg, repaglinide, nateglinide) can be used in patients unusually predisposed to hypoglycemia. Patients with initial HbA1c greater than 9-10% may benefit from initial therapy with 2 oral agents.

In a study by Bellomo-Damato et al, nateglinide was associated with lower risk of hypoglycemia than glyburide in the management of postprandial hyperglycemia in patients with diabetes.^[132]

Failure of initial therapy usually should result in addition of another class of drug rather than substitution (reserve substitution for intolerance to a drug due to adverse effects). Considerable debate exists regarding second agents added to (or used initially in conjunction with) metformin. The time-honored approach is to add an insulin secretagogue (usually titrated to no more than the half-maximal approved dose to reduce risk for hypoglycemia). However, some experts recommend a glitazone because of the positive effects of these drugs on inflammation and the vasculature. If this strategy is used, a moderate dose of glitazone (as opposed to the highest approved dose) should be used. A therapeutic scheme utilized by the author is listed in the image below.

Because glitazones not infrequently cause weight gain and edema, the author usually reserves the use of these agents for patients who cannot use metformin, as a result of intolerance or contraindications. Exceptions to this practice might include patients of relatively normal weight who have marked insulin resistance, such as patients of Asian heritage. Before adding a second agent for a patient who is taking an insulin secretagogue, the clinician should warn the patient about the possibility that the second agent will induce hypoglycemia. In such cases, the dose of the insulin secretagogue, not the newly added agent, should be reduced.

If 2 drugs are unsuccessful, the practitioner may consider adding a third class of oral agents. An alternative would be to add bedtime insulin, usually NPH or glargine, to the initial oral agent or 2-drug combination or add the new injectable drug exenatide. The expense and adverse effect profile of glitazones make the oral triple therapy approach less desirable. The new approach of adding exenatide twice daily to 1 or 2 oral agents (eg, metformin and/or a sulfonylurea) is attractive because of its simplicity (ie, only 2 possible doses of exenatide with easy titration compared with insulin), but its expense may be prohibitive. If insulin is used, the insulin dose is titrated to the fasting glucose concentration, which the patient can measure at home (usually with titration to a maximum bedtime insulin dose of approximately 60 units).

Some patients need reduction of their insulin secretagogue to prevent daytime hypoglycemia as the bedtime insulin is initiated or increased and the fasting glucose concentration is decreased. If exenatide is used, the author monitors fasting and postprandial sugars, expecting a marked flattening of the postprandial rise in glucose concentrations.

Measurement of glucose patterns in patients with type 2 diabetes, particularly those who have central obesity and hepatic steatosis, often reveals that the highest preprandial glucose level of the day is before breakfast (because of disordered hepatic glucose production overnight), with a "stair-step" decrease during the day (after the usual postmeal rise). These higher-than-desired morning glucose values do not necessarily dictate abandonment of the current therapeutic regimen, provided that the HbA1c level is at target.

For patients who primarily have fasting hyperglycemia, bedtime insulin is the easiest way to correct this abnormality. The goal of these combined daytime oral agent plus once-a-day insulin is to lower the fasting glucose level to 100 mg/dL by titrating the insulin. When this target is achieved, the oral agents can be effective in maintaining preprandial and postprandial blood glucose levels throughout the day. If a regimen combining oral agents and insulin fails to lower glucose levels into the normal range, patients should be switched to a daily multiple-injection schedule with a premeal rapid-acting insulin and a longer-acting basal insulin.

A necessary condition for twice-daily insulin to succeed is a regimented lifestyle, with mealtimes regularly spaced and insulin injections taken at essentially the same time every day, including weekends and holidays. Lack of regularity in the schedule is self-defeating for this approach to therapy. . Eating a high-protein pre-breakfast snack, such as one with soy yogurt, is a simplified regimen to achieve better post-breakfast glycemic control, according to a study by Chen et al; this study confirms a phenomenon observed in healthy humans nearly a century ago (Staub, 1921).^[133]

The author limits the use of premixed insulin to patients who might have trouble mixing their insulins. The author also prefers premixes containing regular insulin if the premix is administered to maintain better midday coverage. Premixes with rapid-acting medications can be used if the midday meal is small. All insulin injections should be administered in the abdomen. A systematic review found that glycemic control with premixed insulin analogues (ie, mixtures of rapid-acting and intermediate-acting insulin analogues) is similar to that of premixed human insulin.^[134]

Conventional multiple daily dosing of insulin gives the patient the greatest flexibility. In this approach, insulin glargine or twice-daily insulin detemir is generally given as the basal insulin, and rapid-acting insulin (eg, aspart, glulisine, lispro) are administered just before each meal. The basal component can be administered any time of day as long as it is given at the same time each day. Interpreting glucose patterns is probably easiest if the basal insulin is administered at or near bedtime. The basal insulin can then be titrated to the morning sugar, and the bolus premeal insulin can be titrated to the next premeal sugar and, in some cases, a postprandial (2 h) value.

Adiposity blunts the pharmacodynamics of the basal insulins NPH, detemir, and glargine, especially detemir.^[135]

For patients trying to achieve near euglycemia, premeal glucose values of 80-120 mg/dL are the goal, with the patient going to sleep at night with a value at least 100 mg/dL. In patients with less stringent glycemic goals (eg, because of advanced age, advanced complications, severe concomitant disease), preprandial glucose values of 100-140 mg/dL are desired. Because of the limitations of therapies, essentially no patient is able to achieve these goals all the time if, in fact, insulin is needed to treat their disease.

An intensified basal-bolus regimen of insulin glargine and insulin glulisine provides better glycemic control than does a standard, premixed insulin regimen, in patients with long-standing, insulin-treated type 2 diabetes mellitus, according to a study by Fritsche et al. In this open-label, randomized, multinational trial, an intensified insulin regimen combining insulin glargine (once daily) with premeal insulin glulisine (basal-bolus group; n=153) was compared with twice-daily conventional therapy with premixed insulin (n=157). The mean decrease from baseline HbA1c was -1.31% for the basal-bolus group, versus -0.80% for the premix patients, with more patients in the basal-bolus group attaining HbA1c of 7% or less. Moreover, significantly lower blood glucose levels were observed in the basal-bolus group than in the premix group.^[136]

A study of basal-bolus insulin therapy among patients with type 2 diabetes undergoing general surgery determined that treatment with glargine once daily plus glulisine before meals improved glycemic control while reducing hospital complications when compared with sliding scale regular insulin.^[137]

A study from the ACCORD Study Group confirmed the risk of an increased death rate in high-risk patients when the treatment target for HbA1c is set below 6%.^[138] This strategy is best avoided in high-risk patients in whom nonfatal myocardial infarctions are reduced at the consequence of an increased risk of death.

Incorporating HbA1c measurement significantly improves the ability to predict cardiovascular disease risk compared with classification of diabetes as cardiovascular risk equivalent.^[139]

Unlike in long-standing type 1 diabetes mellitus, patients with type 2 diabetes mellitus usually maintain adequate warning symptoms and signs of hypoglycemia. This situation greatly facilitates hypoglycemic therapy (ie, insulin secretagogues, insulin) in patients with type 2 diabetes.

Glycemic control is a function not only of fasting and preprandial glucose values but also of postprandial glycemic excursions. Emphasis on postprandial glucose measurements has been fueled to some degree by the availability of short-acting insulin secretagogues, very-short-acting insulin, and alpha-glucosidase inhibitors, all of which target postprandial glycemia. While postprandial glucose levels are a better predictor of macrovascular disease risk early in the course of loss of glucose tolerance, it remains to be seen whether targeting after-meal glucose excursions has more of an effect on the risk of complications than do more conventional strategies.

A study by Siegelaar et al seriously questions the notion that targeting postprandial glucose variability favorably affects cardiovascular outcomes in patients after myocardial infarction.^[140] Clearly, more studies are needed to determine the proper action.

Intuitively, one would assume that therapies that normalize preprandial and postprandial glycemia (or that come close to normalizing them) would be optimal. Whether such a strategy can be achieved without untoward adverse effects and with further reductions in microvascular and macrovascular disease risk (compared to regimens used in the UKPDS) with newly available therapies is open to question. Practically speaking, most patients are fully occupied trying to do conventional glucose monitoring and insulin dose adjustment.

An outline of the therapeutic approach generally used by the author is presented in the first 2 images below. An idealized scheme for glucose and insulin patterns is presented in the third image below. The author finds that keeping such an idealized scheme in mind is helpful in treating and educating patients, even if the patient is trying to replicate it with less-intensive insulin therapy.

Decisions about glycemic management are generally made on the basis of HbA1c measurements and the results of self-monitoring blood glucose (SMBG). HbA1c is measured at least twice a year in patients with stable glycemic control who are meeting treatment goals and quarterly in patients whose therapy has changed or who are not meeting treatment goals.^[71] If a total glycosylated hemoglobin (GHb) measurement is used, the actual number is 1-2% higher, but the laboratory should provide a correlation with actual HbA1c values.^{[38, 66, 70]}

A guideline from the American College of Physicians (ACP) recommends that an HbA1c target of less than 7% is appropriate for many patients.^[141] The ACP advises, however, that this target level may not be appropriate for all patients; goals should be tailored to the individual patient and should take into account the patient's preferences, risk for complications from diabetes, comorbidity, and life expectancy. Some organizations (eg, the American Association of Clinical Endocrinologists,^[142] the International Diabetes Federation) recommend a glycemic target of HbA1c less than 6.5%.

Risk for hypoglycemia is almost always the limiting factor in achieving the lowest possible HbA1c that does not cause undue harm. Unfortunately, some practitioners and their patients pursue a particular HbA1c value despite uncertain benefit or unacceptable risk with significant risk for side effects.

Factors that can produce an unfavorable risk-benefit ratio for intensive blood glucose lowering include advanced age, other major systemic disease, and advanced microvascular and neuropathic complications. For example, in an elderly patient, risk considerations might include the possibility of falling and breaking a hip during a hypoglycemic episode. In elderly patients who have a life expectancy of less than 5 years or in any patient with a terminal disease, tight control may be unnecessary. Patients with cardiovascular or cerebrovascular disease may also need higher preprandial blood glucose targets (eg, 100-150 mg/dL) to prevent severe hypoglycemia.

In a meta-analysis of 13 studies, no significant effect of intensive glucose lowering was noted in cases of all cause mortality or cardiovascular deaths. A reduction in nonfatal myocardial infarction and microalbuminuria was noted, with a 2-fold increased risk of hypoglycemia.^[143]

Additionally, patients with alcoholism or other serious substance abuse and patients with severe uncontrolled mental illness may be unable to effectively participate in the care of their diabetes, placing them at high risk for severe hypoglycemic reactions if near-normal glucose levels are targeted. Finally, patients with hypoglycemia unawareness (ie, lack adrenergic warning signs of hypoglycemia) or those with recurrent episodes of severe hypoglycemia (ie, hypoglycemia requiring treatment by another person) should also have high target levels at least temporarily.

Self-monitoring of blood glucose

Daily SMBG is important for patients treated with insulin or insulin secretagogues to monitor for and prevent hypoglycemia and optimize the treatment regimen. The optimal frequency of SMBG for patients with type 2 diabetes is unresolved, but it should be sufficient to facilitate reaching glucose goals. The author often utilizes no or minimal SMBG in patients using lifestyle changes alone or agents that do not cause hypoglycemia (eg, metformin, glitazones, glucosidase inhibitors). Patients using multiple insulin injections should use SMBG at least 3 times a day.^[71]

A task force from the Endocrine Society evaluated 3 potential uses for continuous glucose monitoring: (1) real-time continuous glucose monitoring in adults in hospital settings, (2) real-time outpatient monitoring in children and adolescents, and (3) real-time outpatient monitoring in adults. The Task Force developed recommendations regarding benefits in maintaining target levels of glycemia and limiting the risk of hypoglycemia.^[144]

For most patients, the best diet is one consisting of the foods that they are currently eating. Attempts to calibrate a precise macronutrient composition of the diet to control diabetes, while time-honored, are generally not supported by the research. Caloric restriction is of first importance. After that, individual preference is reasonable. Modest restriction of saturated fats and simple sugars is also reasonable. However, some patients have remarkable short-term success with high-fat, low-carbohydrate diets of various sorts. Therefore, the author always stresses weight management in general and is flexible regarding the precise diet that the patient consumes. Also, the practitioner should advocate a diet using foods that are within the financial reach and cultural milieu of the patient.

Ectopic fat deposition in liver and elsewhere adversely impacts insulin sensitivity. A weight loss strategy in children may help preserve insulin sensitivity.^[145]

Modest weight losses of 5-10% were associated with significant improvements in cardiovascular disease risk factors (ie, decreased HbA1c levels, reduced blood pressure, increase in HDL cholesterol, and decrease in plasma triglycerides) in patients with type 2 diabetes mellitus. Risk factor reduction was even greater with losses of 10-15% of body weight.^[146]

Esposito et al reported greater benefit from a low-carbohydrate, Mediterranean-style diet compared with a low-fat diet in patients with newly diagnosed type 2 diabetes mellitus.^[147] In a single-center, randomized trial, 215 overweight patients with newly diagnosed type 2 diabetes mellitus who had never been treated with antihyperglycemic drugs and whose HbA1c levels were less than 11% were assigned to either a Mediterranean-style diet (< 50% of daily calories from carbohydrates) or a low-fat diet (< 30% of daily calories from fat).

After 4 years, participants assigned to the Mediterranean-style diet had lost more weight and had demonstrated more improvement in some measures of glycemic control and coronary risk than had participants consuming the low-fat diet; 44% of patients in the Mediterranean-style diet group required antihyperglycemic drug therapy, compared with 70% of those in the low-fat diet group.

A study by Larsen et al concluded a high-protein diet offers no superior long-term therapeutic beneficial effect compared with a high-carbohydrate diet in the treatment of type 2 diabetes mellitus.^[148]

Already attenuated glucose disposal is not worsened by postprandial circulating amino acid concentration. Therefore, recommendations to restrict dietary proteins in patients with type 2 diabetes seem unwarranted.^[149]

A study by Lazo et al attested to the benefits of lifestyle intervention, which aimed at a minimum weight loss of 7%, on hepatic steatosis in those with type 2 diabetes.^[150] Since there is no known treatment of nonalcoholic fatty liver disease, a weight loss strategy might help prevent progression to serious liver damage.

In the Cardiovascular Health Study, phospholipid trans -palmitoleate levels were found to be associated with lower metabolic risk.^[151] Trans -palmitoleate is principally derived from naturally occurring dairy and other ruminant trans -fats. Circulating trans -palmitoleate is associated with lower insulin resistance, incident of diabetes, and atherogenic dyslipidemia. Potential health benefits, therefore, need to be explored.

Food-derived pro-oxidant advanced glycation end products may contribute to insulin resistance in clinical type 2 diabetes mellitus and may suppress protective mechanisms. Advanced glycation end product restriction may preserve native defenses and insulin sensitivity by maintaining a lower basal oxidative state.^[152]

Oral ginseng (or ginsenoside) does not improve pancreatic beta cell function. Routine use is not recommended.^[153]

Pasta enriched with biologically active isoflavone aglycons improves endothelial function in patients with type 2 diabetes mellitus and favorably affects CVD risk markers.^[154]

Most patients with type 2 diabetes mellitus can benefit from increased activity. Aerobic exercise improves insulin sensitivity and may improve glycemia markedly in some patients.

Structured exercise training of more than 150 minutes per week is associated with greater HbA1c reduction; however, physical activity helps lower HbA1c only when combined with dietary modifications.^[155]

The patient should choose an activity that she or he is likely to continue. Walking is accessible to most patients in terms of time and financial expenditure.

A previously sedentary patient should start activities slowly.

Older patients, patients with long-standing disease, patients with multiple risk factors, and patients with previous evidence of atherosclerotic disease should have a cardiovascular evaluation, probably including an imaging study, prior to beginning a significant exercise regimen.

In diabetic adolescents and children, nocturnal hypertension was significantly associated with daytime blood pressure and carotid intima-media thickness (cIMT), which could be precursors to atherosclerotic cardiovascular disease later in life. This study warrants confirmation and longitudinal follow-up.^[156]

Balducci et al showed that a supervised facility-based exercise training program, when added to standard treatments for type 2 diabetes mellitus, yields better and beneficial results, compared with simply counseling patients to exercise.^[157]

A randomized, controlled trial emphasized the need to incorporate both aerobic and resistance training to achieve better lowering of A1c levels.^[158]

Aerobic exercise alone or in combination with resistance training improves glycemic control, circulating triglycerides, systolic blood pressure, and waist circumference.^[159] The impact of resistance exercise alone, however, remains unclear.

Loimaala et al found that long-term endurance and strength training resulted in improved metabolic control of diabetes mellitus and significant cardiovascular risk reduction, compared with standard treatment. However, exercise training did not improve conduit arterial elasticity.^[160]

Yoga can be effective in reducing oxidative metabolic stress in patients with type 2 diabetes mellitus but does not impact waist-to-hip ratio, blood pressure, vitamin E, or superoxide dismutase.^[161]

Because diabetes mellitus is a multisystem disease, focusing solely on blood sugar is inadequate. The image below lists appropriate laboratory parameters in the global assessment of patients with type 2 diabetes mellitus. Obviously, patients with abnormalities need more frequent monitoring to guide therapeutic interventions. Drug-specific monitoring is also necessary (eg, serum creatinine for metformin, serum transaminases for glitazones).

The ADA recommends initiation of complications monitoring at the time of diagnosis of diabetes mellitus.^[71] This regimen should include yearly dilated eye examinations, yearly microalbumin checks, and foot examinations at each visit.

A study by Cigolle et al found that middle-aged and older adults with diabetes have an increased risk for the development of geriatric conditions.^[162] These conditions substantially contribute to morbidity and functional impairment. The authors concluded that adults with diabetes should be monitored for the development of geriatric conditions at a younger age than was previously considered.

For example, the risk for early development of Parkinson disease is 36% higher in those with diabetes mellitus.^[163] However, a systematic review from Cereda et al found no conclusive evidence on this association.^[164]

Additionally, a high overall risk for pancreatic neoplasm is noted in individuals with diabetes mellitus, particularly in those aged 45-65 years.^[165]

Incidence of complications widely vary among the Asian subgroups, suggesting the need for an ethnic stratified nuanced approach in evaluation and surveillance.^[166] One size does not fit all.

The role of hypertension in increasing microvascular and macrovascular risk in patients with diabetes mellitus has been confirmed in the UKPDS and Hypertension Optimal Treatment (HOT) trials.^{[167, 168]} The ADA suggests that the BP goal be below 130/80 mm Hg. In patients with greater than 1 g/d proteinuria and renal insufficiency, a more aggressive therapeutic goal (ie, 125/75 mm Hg) is advocated. According to the Veterans Affairs Diabetes Trial, a diastolic blood pressure of less than 70 mm Hg increases the risk of cardiovascular disease in patients with diabetes, even when systolic blood pressure is within the current guidelines (recommended range, < 140 mm Hg).^[169]

While ACE inhibitors, angiotensin receptor blockers (ARB), diuretics, beta blockers, and calcium channel blockers are all considered acceptable initial therapy, the author prefers inhibitors of the renin-angiotensin system (ie, ACE inhibitors, ARB) because of their proven renal protection effects in patients with diabetes. Many patients require multiple agents. Diuretics or calcium channel blockers frequently are useful as second and third agents.

A study by Fogari et al found that, compared with amlodipine, the angiotensin II receptor antagonist losartan provided greater attenuation of left ventricular hypertrophy in hypertensive patients with type 2 diabetes.^[170]

A study by Hermado et al showed that treatment with antihypertensive medications taken at bedtime provide better ambulatory blood pressure control as well as significant reduction in cardiovascular morbidity and mortality when compared with taking medications upon waking.^[171]

The addition of the ARB telmisartan to usual care in patients at high risk for CVD did not prevent incident diabetes or lead to regression of IFG or IGT.^[172]

Dyslipidemia is common in patients with type 2 diabetes mellitus and often takes the form of high triglycerides and low high-density lipoprotein cholesterol (HDL-C) levels. Data from statin trials show that event reduction is achievable in secondary prevention (ie, patients with diabetes and known coronary heart disease (CHD) and elevated levels of low-density lipoprotein cholesterol [LDL-C]).

Fibrates may reduce CHD events in patients with isolated low HDL-C. Primary prevention studies have also now shown that statin therapy reduces CHD events. Whether therapy aimed more at triglyceride reduction and HDL-C elevation (ie, fibrates, niacin) is effective in CHD event reduction in primary prevention remains to be determined. The ADA guidelines for therapy of elevated LDL-C are presented in the image below.^[173]

A study by Davis et al determined that fenofibrate reduced albuminuria and slowed the estimated glomerular filtration rate loss over 5 years in patients with type 2 diabetes mellitus.^[174] Despite initially increasing plasma creatinine, which was reversible, fenofibrate may delay albuminuria and glomerular filtration rate impairment. However, further studies are needed.

Vasoconstricting beta-blockers are known to reduce HDL-C levels and increase triglyceride, LDL-C, and total cholesterol levels. The vasodilating beta-blocker carvedilol (mixed alpha1, beta1, and beta2-blocker) has not been associated with the aforementioned effects. A randomized, double-blind trial in patients with type 2 diabetes mellitus receiving renin-angiotensin blockers compared the effects of metoprolol (a vasoconstricting beta-blocker) with carvedilol on serum lipid concentrations.^[175] The results showed that the addition of carvedilol for blood pressure control resulted in a significant decrease in triglyceride, total cholesterol, and non–HDL-C levels. Patients using metoprolol were significantly more likely to be started on statin therapy or, if already on statin therapy, to require an increase in the dose, than were patients taking carvedilol.

Although the risk for CHD is 2-4 times greater in patients with diabetes than in individuals without diabetes, control of conventional risk factors is probably more important in event reduction than glycemic control. Control of hypertension, aspirin therapy, and LDL-C lowering are vitally important in reducing CHD risk.

The ADA recommends that patients with diabetes who are at high risk for cardiovascular events receive primary preventive therapy with low-dose enteric-coated aspirin. For patients with aspirin hypersensitivity or intolerance, clopidogrel is recommended.^[176] However, a randomized, controlled trial from Japan found that low-dose aspirin as primary prevention did not reduce the risk of cardiovascular events in patients with type 2 diabetes.^[177]

A study by Saito et al determined that low-dose aspirin therapy favorably impacts (primary prevention) cardiovascular endpoints only in patients with a GFR of 60-89 mL/min.^[178] The low-dose aspirin therapy has no beneficial impact if the GFR is above 90 mL/min or below 60 mL/min. However, the trial was restricted to Japanese individuals.

A study by Okada et al reported that low-dose aspirin (81-100 mg) therapy in patients with diabetes who are taking insulin or oral hypoglycemic agents does not reduce atherosclerotic events.^[179] This is yet another argument against using low-dose aspirin for primary prevention of cardiovascular disease in patients with moderate or severe diabetes.

The Scandinavian Simvastatin Survival Study (4S) showed a 42% reduction in CHD events in patients with diabetes with known CHD and very high LDL-C levels with simvastatin therapy (mean dose 27 mg/d, with LDL-C reduction approximately 35%).^[180] A smaller reduction was seen in the Heart Protection Study (HPS) in patients with CHD or other vascular disease and diabetes.^[181] Lesser degrees of risk reduction have been shown in other secondary prevention studies in patients treated with pravastatin with mild-to-moderate LDL-C elevation at baseline.

Intensive-dose statin therapy was associated with increased risk of new onset diabetes compared with moderate dose in a pooled analysis of data from 5 statin trials.^[182] Use of statins in postmenopausal women may increase risk of type 2 diabetes; however, this needs to be further substantiated.^[183] Until such time, current guidelines for the primary and secondary prevention of cardiovascular disease must remain unaltered.

Atorvastatin, 10 mg daily, did not reduce CHD risk among diabetic patients with hypertension and no previous CHD enrolled in the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT).^[184] In contrast, the Collaborative Atorvastatin Diabetes Study (CARDS) did show a significant reduction in CHD risk in patients with type 2 diabetes mellitus and 1 other risk factor when treated with atorvastatin 10 mg daily.^[185] The diabetic subgroup of HPS without previous vascular disease also showed a significant reduction in events when treated with simvastatin 40 mg daily compared to placebo.

The ARB olmesartan delays or prevents microalbuminuria that is not explained on the basis of blood pressure reduction.^[186] However, it increases the risk of cardiovascular events in patients with preexisting cardiovascular disease.

Epidemiologic studies suggest that the LDL-C goal in patients with type 2 diabetes mellitus should be 100 mg/dL or less. There is contradictory epidemiologic evidence as to whether diabetes is in fact a CHD risk equivalent, but for the moment, that is the dogma adopted by most groups, such as the National Cholesterol Education Program (NCEP) and ADA.^[173]

Small studies have led to a suggestion that a lower LDL-C goal, of less than 70 mg/dL, be considered in patients at very high risk, including patients with diabetes. However, the NCEP lists this as a therapeutic option rather than a formal recommendation as of this writing. The ADA guidelines for LDL-C are listed in the image below.

Whether therapy to reduce triglycerides, a common abnormality in type 2 diabetes mellitus, is efficacious in reducing events has not been determined from clinical end-point trials.

The diabetic subgroup in the Veterans Administration HDL Intervention Trial (VA-HIT) showed approximately 22% reduction in CHD events in patients with diabetes and known CHD when HDL-C was increased by approximately 6% by gemfibrozil.^[187] This was a low LDL-C population, so whether these same benefits would accrue in patients with elevated LDL-C who are treated with a statin before addressing their low HDL-C is unclear. Some of the statin trials suggest that statin therapy eliminates some of the excess risk for low HDL-C in patients with LDL-C elevation at baseline.

The Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) study reported on 2368 patients with type 2 diabetes mellitus and heart disease who were randomized into 4 groups: those who received prompt revascularization with intensive medical therapy, those who received intensive medical therapy alone, those who underwent insulin-sensitization therapy, and those who received insulin-provision therapy.^[188]

After 5 years, results from the BARI 2D study showed no significant difference in the rates of death and major cardiovascular events between patients undergoing prompt revascularization and those undergoing medical therapy. Additionally, no difference was shown between insulin sensitization and insulin provision. These data emphasize the need to customize therapy to the patient’s circumstances and therapeutic goals.

Patients with established retinopathy should see an ophthalmologist every 6-12 months or more often as necessary. Three-year retinal screening may be feasible for patients with mild diabetes and no retinopathy.^[189]

Early background retinopathy may reverse with improved glycemic control. More advanced retinopathy does not regress with improved glycemia and may worsen, although rarely, with short-term marked improvements in glycemia. Hypertension control is of paramount importance in these latter patients.

Laser photocoagulation has markedly improved the ability of ophthalmologists to preserve sight in patients with diabetes and proliferative retinopathy or macular edema.

Results of the randomized, placebo-controlled DIRECT-Protect 2 trial suggested that treatment with the ARB candesartan might improve mild to moderate retinopathy in patients with type 2 diabetes.^[190]

Macular edema has been reported in a proportion of patients who experience fluid retention as a side effect of glitazones.^[191] Resolution typically follows cessation of the glitazone, although diuretics have been prescribed in such cases.

Diabetes can affect the lens, vitreous, and retina, causing visual symptoms that may prompt the patient to seek emergency care. Visual blurring may develop acutely as the lens changes shape with marked changes in blood glucose concentrations. This effect, which is caused by osmotic fluxes of water into and out of the lens, usually occurs as hyperglycemia increases, but it also may be seen when high glucose levels are lowered rapidly. In either case, recovery to baseline visual acuity can take up to a month, and some patients are almost completely unable to read small print or do close work during this period.

Patients with diabetes also tend to develop senile cataracts sooner than persons without diabetes, though this is not related to the degree of glycemic control.

Using nailfold video capillaroscopy, a high prevalence of capillary changes is detected in patients with diabetes, particularly those with retinal damage. This reflects a generalized microvessel involvement in both type 1 and type 2 diabetes.^[192]

Whether patients develop diabetic retinopathy depends on the duration of their diabetes and on the level of glycemic control maintained.^{[193, 194]} Because the diagnosis of type 2 diabetes often is delayed, 20% of these patients have some degree of retinopathy at diagnosis. The following are the 5 stages in the progression of diabetic retinopathy:

• Dilation of the retinal venules and formation of retinal capillary microaneurysms
• Increased vascular permeability
• Vascular occlusion and retinal ischemia
• Proliferation of new blood vessels on the surface of the retina
• Hemorrhage and contraction of the fibrovascular proliferation and the vitreous

The first 2 stages of diabetic retinopathy are known as background or nonproliferative retinopathy. Initially, the retinal venules dilate, then microaneurysms (tiny red dots on the retina that cause no visual impairment) appear. As the microaneurysms or retinal capillaries become more permeable, hard exudates appear, reflecting the leakage of plasma. Larger retinal arteriolar and venular calibres were associated with lower scores on memory tests but not with lower scores on other cognitive tests.^[195] This association was strong in men. Impaired arteriolar autoregulation may be an underlying mechanism of memory decrements.

Rupture of intraretinal capillaries results in hemorrhage. If a superficial capillary ruptures, a flame-shaped hemorrhage appears. Hard exudates are often found in partial or complete rings (circinate pattern), which usually include multiple microaneurysms. These rings usually mark an area of edematous retina. The patient may not notice a change in visual acuity unless the center of the macula is involved.

Macular edema can cause visual loss; therefore, all patients with suspected macular edema must be referred to an ophthalmologist for evaluation and possible laser therapy. Laser therapy is effective in decreasing macular edema and preserving vision but is less effective in restoring lost vision.

Preproliferative and proliferative diabetic retinopathy are the next stages in the progression of the disease. Cotton-wool spots can be seen in preproliferative retinopathy. These represent retinal microinfarcts caused by capillary occlusion and appear as patches that range from off-white to gray and have poorly defined margins.

Proliferative retinopathy is characterized by neovascularization, or the development of networks of fragile new vessels that often are seen on the optic disc or along the main vascular arcades. The vessels undergo cycles of proliferation and regression. During proliferation, fibrous adhesions develop between the vessels and the vitreous. Subsequent contraction of the adhesions can result in traction on the retina and retinal detachment. Contraction also tears the new vessels, which hemorrhage into the vitreous.

Patients with preproliferative or proliferative retinopathy must immediately be referred for ophthalmologic evaluation because laser therapy is effective in this condition, especially before actual hemorrhage occurs.

Often, the first hemorrhage is small and is noted by the patient as a fleeting, dark area, or "floater," in the field of vision. Because subsequent hemorrhages can be larger and more serious, the patient should be referred immediately to an ophthalmologist for possible laser therapy. Patients with retinal hemorrhage should be advised to limit their activity and keep their head upright (even while sleeping), so that the blood settles to the inferior portion of the retina, thus obscuring less central vision.

Patients with active proliferative diabetic retinopathy are at increased risk of retinal hemorrhage if they receive thrombolytic therapy; therefore, this condition is a relative contraindication to the use of thrombolytic agents.

One study has shown that individuals with gingival hemorrhaging have a high prevalence of retinal hemorrhage.^[196] Much of this association is driven by hyperglycemia making it possible to use gingival tissue to study the natural course of microvascular disease in patients with diabetes.

For more information, see Macular Edema in Diabetes

Peripheral neuropathy is the most common complication observed in patients with type 2 diabetes in outpatient clinics. Patients may have paresthesias, numbness, or pain. The feet are involved more often than the hands.

Improved glycemic control early may alleviate some of the symptoms, although sometimes symptoms actually worsen with lowering of blood glucose levels. Later symptomatic therapy largely is empiric, including low-dose tricyclic antidepressants, duloxetine, anticonvulsants (eg, phenytoin, gabapentin, carbamazepine), topical capsaicin, and various pain medications, including nonsteroidal anti-inflammatory drugs.

Protection of the feet by applying lubricating agents (but not between the toes) and wearing appropriate footwear (shoes and socks or stockings) is important. Daily inspection of the feet after bathing is mandatory. In patients with advanced neuropathy, water temperature must be checked by a companion or with a thermometer. Soaking the feet generally is not recommended and may be harmful.

Gastroparesis is usually less of a problem in patients with type 2 diabetes mellitus than in those with type 1. Improved glycemic control, discontinuation of medications that slow gastric motility, and the use of metoclopramide may be helpful. Metoclopramide use preferably should be limited to a few days at a time, as long-term use has been linked to tardive dyskinesia.^[197]

Autonomic neuropathy may manifest as orthostatic hypotension. Such patients may require volume expanders or adrenergic agents.

Patients with cystopathy may benefit from cholinergic agents.

Acute-onset mononeuropathies in diabetes include acute cranial mononeuropathies, mononeuropathy multiplex, focal lesions of the brachial or lumbosacral plexus, and radiculopathies. It is important to consider nondiabetic causes for cranial nerve palsies, including intracranial tumors, aneurysms, and brainstem stroke.^[198]

For more information see Diabetic Neuropathy and Diabetic Lumbosacral Plexopathy.

Diabetes predisposes patients to a number of potential infectious diseases, including the following:

• Malignant otitis externa
• Rhinocerebral mucormycosis
• Bacteriuria
• Pyuria
• Cystitis
• Upper urinary tract infection
• Intrarenal bacterial infection
• Skin and soft tissue infections
• Osteomyelitis

Ear, nose, and throat infections

Malignant otitis externa and rhinocerebral mucormycosis, 2 head and neck infections that are associated with high rates of morbidity and mortality, are seen almost exclusively in patients with diabetes.

Malignant or necrotizing otitis externa principally occurs in patients with diabetes who are older than 35 years and is almost always due to Pseudomonas aeruginosa.^[199] The term malignant otitis externa has been applied to several different clinical entities—severe otitis externa, perichondritis, and temporal bone osteomyelitis—which may coexist.

Infection starts in the external auditory canal and spreads to adjacent soft tissue, cartilage, and bone. Patients typically present with severe ear pain and otorrhea. Fever may be absent. Although patients often have preexisting otitis externa, progression to invasive disease is usually rapid.

Examination of the auditory canal may reveal granulation tissue, but spread of infection to the pinna, preauricular tissue, and mastoid often makes the diagnosis apparent. Involvement of the cranial nerves, particularly the facial nerve, is common; when infection extends to the meninges, it is often lethal. CT or MRI helps to define the extent of disease.

Prompt surgical consultation is mandatory for malignant otitis externa because surgical debridement is often an essential part of therapy. Intravenous antipseudomonal antibiotics should be started immediately in patients with invasive disease. Patients with diabetes with severe otitis externa but no evidence of invasive disease can be treated with an otic antibiotic drop and oral ciprofloxacin; they require close follow-up.

Rhinocerebral mucormycosis collectively refers to infections caused by various ubiquitous molds.^[200] Invasive disease occurs in patients with poorly controlled diabetes, especially those with diabetic ketoacidosis. Organisms colonize the nose and paranasal sinuses, spreading to adjacent tissues by invading blood vessels and causing soft tissue necrosis and bony erosion.

Patients with rhinocerebral mucormycosis usually present with periorbital or perinasal pain, swelling, and induration. Bloody or black nasal discharge may be present. Involvement of the orbits, with lid swelling, proptosis, and diplopia, is common. The nasal turbinates may appear dusky red, ulcerated, or frankly necrotic. Black necrotic nasal mucosal or palatal tissue is an important visual clue. The infection may invade the cranial vault through the cribriform plate, resulting in cerebral abscess, cavernous sinus thrombosis, or thrombosis of the internal carotid artery.

Wet smears of necrotic tissue often reveal broad hyphae and distinguish mucormycosis from severe facial cellulitis. CT or MRI helps to delineate the extent of disease. Treatment consists of controlling the predisposing hyperglycemia and acidemia, giving intravenous amphotericin B, and immediate surgical debridement. Until the diagnosis is confirmed, antistaphylococcal antibiotic therapy is appropriate

Urinary tract infections

Patients with diabetes have an increased risk of asymptomatic bacteriuria and pyuria, cystitis and, more important, serious upper urinary tract infection. Intrarenal bacterial infection should be considered in the differential diagnosis of any patient with diabetes who presents with flank or abdominal pain.

The treatment of cystitis is essentially the same as that in patients without diabetes, except that longer courses of therapy are generally recommended (eg, 7 d for uncomplicated cystitis). Individuals with a neurogenic bladder due to diabetic neuropathy may not empty their bladder well and may require urologic referral.

Treatment of pyelonephritis does not differ for patients with diabetes, but a lower threshold for hospital admission is appropriate. First, pyelonephritis makes control of diabetes more difficult by causing insulin resistance; in addition, nausea may limit the patient's ability to maintain normal hydration. The ensuing hyperglycemia further compromises their immune response. Second, patients with diabetes are more susceptible than others to complications of pyelonephritis (eg, renal abscess, emphysematous pyelonephritis, renal papillary necrosis, gram-negative sepsis).

Emphysematous pyelonephritis is an uncommon necrotizing renal infection caused by Escherichia coli,Klebsiella pneumoniae, or other organisms capable of fermenting glucose to carbon dioxide.^[201] The presentation is usually similar to that of uncomplicated pyelonephritis, and the diagnosis is established by identifying renal gas on plain radiography, CT, or sonography. Surgery is indicated after diagnosis.

Skin and soft tissue infections

Sensory neuropathy, atherosclerotic vascular disease, and hyperglycemia all predispose patients with diabetes to skin and soft tissue infections. These can affect any skin surface but most commonly involve the feet.

To see complete information on Bullous Disease of Diabetes, please go to the main article by clicking here.

Cellulitis, lymphangitis, and, most ominously, staphylococcal sepsis can complicate even the smallest wound. Minor wound infections and cellulitis are typically caused by Staphylococcus aureus or hemolytic streptococci.

Treatment with a penicillinase-resistant synthetic penicillin or a first-generation cephalosporin has been effective for the outpatient treatment of minor infections, but the increasing prevalence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) must now be considered when selecting an antibiotic. Rates of CA-MRSA do not appear to be higher in patients with diabetes than in comparable patients without diabetes.

Outpatient treatment of minor infections is appropriate for patients who are reliable, who monitor their blood glucose and urine ketone levels, and who have access to close follow-up.

Necrotizing infections of the skin, subcutaneous tissues, fascia, or muscle can also complicate wounds, particularly cutaneous ulcers. These infections are typically polymicrobial, involving group A streptococci, enterococci, S aureus, Enterobacteriaceae, and various anaerobes. Radiographs of any spreading soft tissue infection in a patient with diabetes should be obtained to look for the soft tissue gas that characterizes necrosis. Gram stains and surface cultures are not helpful.

Surgical debridement is necessary for necrotizing infections. Antibiotic coverage should reflect the range of potential pathogens.

To see complete information on Diabetic Ulcers, please go to the main article by clicking here.

Osteomyelitis

Contiguous spread of a polymicrobial infection from a skin ulcer to adjacent bone is common in patients with diabetes, particularly from chronic ulcers.

In one study, osteomyelitis was found in the bone under 68% of diabetic foot ulcers, and findings on physical examination and plain radiographs did not help in diagnosing one half of the cases.^[202] Unfortunately, these diagnostic modalities are often the only ones available in the ED, and the diagnosis might be suspected but not established. MRI, if available on an emergent basis, has better sensitivity and specificity in diagnosing osteomyelitis.^[203]

Cultures from superficial wound swabs often fail to identify the causative organism. Cultures from biopsy or curettage of the debrided ulcer base are preferred. If osteomyelitis is apparent on physical examination (eg, if the wounds are deep enough to expose tendons or bone), radiography, or MRI, the patient should be admitted for intravenous antibiotics. If osteomyelitis is suspected but the soft tissue infection or metabolic disturbances do not warrant admission, the patient can be discharged for outpatient workup.

Other infections

Although cholecystitis is probably no more common in patients with diabetes than in the general population, severe fulminating infection, especially with gas-forming organisms, is more common. The early clinical manifestations of emphysematous cholecystitis are indistinguishable from those of usual cholecystitis. The diagnosis can be made by finding gas in the gallbladder lumen, wall, or surrounding tissues. Gallstones are present in only approximately 50% of cases. Perforation is common, and, even with immediate surgery, the rate of mortality is high. Infection is typically polymicrobial. Clostridial species are found in more than 50% of cases.

The incidence of staphylococcal and K pneumoniae infections are greater in people with diabetes than in people without diabetes, and cryptococcal infections and coccidioidomycoses are more virulent in patients with diabetes. Also, diabetes is a risk factor for reactivation of tuberculosis. However, a study from Denmark, a country with low tuberculosis burden, found no evidence of association between tuberculosis and dysglycemia.^[204]

Surgical patients may experience worsening of glycemia for reasons similar to those listed above for intercurrent medical illness. Patients on oral agents may need transient therapy with insulin to maintain blood glucose at approximately 100-180 mg/dL. In patients who require insulin, scheduled doses of insulin, as opposed to sliding scale insulin, are far more effective in controlling glucose. Intensive glucose control in surgical ICU patients appears to reduce risk of septicemia, but as with other critically ill patients, this may come at the cost of increased risk of hypoglycemia.^[205]

For patients who can eat soon after surgery, the time-honored approach of administering half the usual morning dose of neutral protamine Hagedorn (NPH) insulin with 5% dextrose in the IV infusion is acceptable, with resumption of scheduled insulin (perhaps at reduced doses) within the first 1-2 days.

Patients receiving insulin glargine can often receive their usual dose if they are given intravenous glucose during surgery with appropriate intraoperative and postoperative monitoring of glucose. Oral antidiabetic agents can be restarted when the patient is stable and eating.

Insulin secretagogues should be used with caution in the hospital, since food intake may be interrupted by diagnostic tests and procedures. Metformin may have to be started at a lower dose and gradually titrated to full dose due to gastrointestinal side effects. Since glitazones have such a long biologic effect, their omission in the hospital is usually inconsequential. The role of incretins in the hospital has not yet been defined.

For patients who require more prolonged periods without oral nutrition and for major surgery, such as coronary artery bypass grafting and major abdominal surgery, constant infusion intravenous insulin is preferred. Discontinue metformin temporarily after any major surgery until the patient is clearly hemodynamically stable and normal renal function is documented. The practice of discontinuing metformin for at least 48 hours in this situation until proof of normal renal function is established is sound.

Bariatric surgery

In morbidly obese patients, bariatric surgery has been shown to improve diabetes control and, in some situations, normalize glucose tolerance. It is certainly a reasonable alternative in carefully selected patients if an experienced team (providing appropriate preoperative evaluation as well as technical surgical expertise) is available.

In 2011, the International Diabetes Federation Taskforce on Epidemiology and Prevention of Diabetes released a position statement on bariatric surgery as an appropriate treatment for people with type 2 diabetes mellitus and obesity who have been unable to achieve recommended treatment targets using medical therapies, particularly if other major comorbidities exist.^{[206, 207]}

Guidelines from the American College of Clinical Endocrinologists for prevention of type 2 diabetes mellitus in patients at risk recommend weight reduction, proper nutrition, regular physical activity, cardiovascular risk factor reduction, and aggressive treatment of hypertension and dyslipidemia.

The Diabetes Prevention Program (DPP) trial has shown that modest lifestyle changes (eg, 4-5% sustained weight reduction for approximately 3 y) reduce risk for diabetes in patients at high risk by 58%.^[208] Eight healthcare facilities participated in an instructive study that should help other agencies/states emulate strategies used to affect positive lifestyle changes for the prevention of diabetes.^[209] Drugs from several classes have been studied in the prevention of diabetes. In the DPP, metformin 1700 mg daily was about half as effective as lifestyle intervention in reducing risk.^[208]

Analysis of available data from the DPP suggests that troglitazone was effective in preventing diabetes. This effect was also seen in the Troglitazone in Prevention of Diabetes (TRIPOD) study of Hispanic women with a history of gestational diabetes; after troglitazone was withdrawn from the market because of hepatotoxicity, the continuation of TRIPOD n the Pioglitazone in the Prevention of Diabetes Study demonstrated slowed progression of subclinical atherosclerosis with glitazone treatment.^[210]

In an 11-year follow-up of men and women without evidence of diabetes, heart disease, or cancer at baseline, good lifestyle decisions in combination significantly reduced the risk of developing diabetes.^[211]

The 2010 American Heart Association-American Stroke Association (AHA-ASA) guidelines for the primary prevention of stroke make the following recommendations:^[212]

• Hypertension: Regular blood pressure screening, lifestyle modification and drug therapy are recommended. A lower risk of stroke and cardiovascular events are seen when systolic blood pressure levels are < 140 mm Hg and diastolic blood pressure < 90 mm Hg. In patients that have hypertension with diabetes or renal disease, the blood pressure goal is < 130/80 mm Hg.
• Diabetes: Blood pressure control is recommended in type 1 and 2 diabetes. Hypertensives agents that are useful in the diabetic population include angiotensin converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs). Treating adults with diabetes with statin therapy, especially patients with other risk factors, is recommended, and monotherapy with fibrates may also be considered to lower stroke risk. Taking aspirin is reasonable in patients that are at high CVD risk; however, the benefit of taking aspirin in diabetic patients for the reduction of stroke risk has not been fully demonstrated.
• Dyslipidemia : Treating patients with HMG-CoA reductase inhibitors, also known as statins is recommended in patients with coronary heart disease or certain high-risk conditions for the primary prevention of ischemic stroke. In addition to statin therapy, therapeutic lifestyle changes and LDL-cholesterol goals are also recommended. Niacin may be used in patients with low HDL cholesterol or elevated lipoprotein (a), but its efficacy in preventing ischemic stroke is not established. Fibric-acid derivatives, niacin, bile acid sequestrants and ezetimibe may be useful in patients who have not achieved target LDL with statin therapy or cannot tolerate statins however; their effectiveness in reducing the risk of stroke has not been established.
• Diet and Nutrition: A diet that is low in sodium and high in potassium is recommended to reduce blood pressure. Diets that promote the consumption of fruits, vegetables, and low-fat dairy products such as the DASH-style diet help lower blood pressure and may lower risk of stroke.
• Physical Inactivity: Increasing physical activity is associated with a reduction in the risk of stroke. The goal is to engage in ≥30 minutes of moderate intensity activity on a daily basis.

Acarbose was shown in the Study to Prevent Non-Insulin Dependent Diabetes Mellitus (STOP-NIDDM) to reduce diabetes rates by approximately 25% in patients at high risk for the development of type 2 diabetes.^[213]

In the Diabetes REduction Assessment with ramipril and rosiglitazone Medication (DREAM) trial, investigators concluded that rosiglitazone at 8 mg daily reduces the incidence of type 2 diabetes mellitus in patients with impaired fasting glucose and/or impaired glucose tolerance. At the end of this prospective multicenter study, composite outcome of diabetes or death from any cause was 11.6% in the rosiglitazone group versus 26% in the placebo group.^[214] Reported separately were the data on the use of ramipril up to 15 mg per day versus placebo. This did not show significant reduction in the same composite outcome.^[215]

The U.S. Food and Drug Administration (FDA) has not approved any drug for the treatment of pre-diabetes or the prevention of type 2 diabetes.^[216] The ADA recommends that, in addition to lifestyle counseling, metformin be considered in patients with pre-diabetes who are obese and younger than 60 years and have both impaired fasting glucose and impaired glucose tolerance, in addition to other risk factors (eg, HbA1C >6%, hypertension, low HDL cholesterol, elevated triglycerides, or a family history of diabetes in a first-degree relative).^[71]

Yeh et al found that although cigarette smokers are at increased risk for type 2 diabetes, smoking cessation leads to higher short-term risk.^[217] In a prospective cohort study in 10,892 middle-aged nondiabetic adults, 1254 persons developed type 2 diabetes during 9 years of follow up. The adjusted hazard ratio of incident diabetes among persons in the highest tertile of pack-years was 1.42, compared with persons who had never smoked. However, in the first 3 years after quitting smoking, the hazard ratio was 1.73; the risk then gradually decreased and disappeared completely at 12 years. Yeh et al recommend that smoking cessation in smokers at risk for diabetes be coupled with strategies for prevention and early detection of diabetes.

A study by Jones et al reported that testosterone replacement is associated with favorable impact on insulin resistance, total and LDL cholesterol, and sexual health.^[218]

A significant inverse correlation has been found between magnesium intake and the risk of diabetes.^[219]

Patients with intercurrent illness become more insulin resistant because of the effects of increased counter-regulatory (ie, anti-insulin) hormones. Therefore, despite decreased nutritional intake, glycemia may worsen. Patients on oral agents may need transient therapy with insulin to achieve adequate glycemic control. In patients who require insulin, scheduled doses of insulin, as opposed to sliding scale insulin, are far more effective in achieving glycemic control.^{[220, 221]} If patients taking metformin have any illness that leads to dehydration or hypoperfusion, the drug should be temporarily discontinued because of a possible increased risk of lactic acidosis.

Standard practice in intensively ill patients has been to provide tight glycemic control through intensive insulin therapy. Research evidence, however, has called this practice into question. A meta-analysis found that in critically ill adult patients, tight glucose control is associated with an increased risk of hypoglycemia but not with significantly reduced hospital mortality.^[205] A large, international, randomized trial among adults treated in an intensive care unit (ICU) found that intensive glucose control (target, 81-108 mg/dL) resulted in higher mortality than did a blood glucose target of 180 mg/dL or less.^[222]

Results of the Diabetes and Insulin-Glucose Infusion in Acute Myocardial Infarction (DIGAMI) trial suggested improved outcomes in patients with type 2 diabetes with acute myocardial infarction or stroke who receive constant intravenous insulin during the acute phase of the event to maintain blood glucose values of approximately 100-150 mg/dL.^[223] However, these results were not confirmed in the follow-up trial, DIGAMI-2.^[224]

A post-hoc analysis of the DIGAMI-2 study revealed that glucose-lowering drugs impact prognosis differently. Insulin may be associated with increased risk of nonfatal cardiac events, whereas metformin seems to be protective against risk of death.^[225]

In the case of cardiac ischemia, the beneficial effects of insulin therapy may be due to reduction in free fatty acids.

Primary care providers can care for patients with type 2 diabetes mellitus adequately. The multiple facets of disease treatment (eg, nutrition, exercise, smoking cessation, medications, complications monitoring) and data management (eg, glucose levels, BP, lipids, complications monitoring) must be continually addressed. Inability to achieve adequate glycemic (or BP or lipid) control usually should be a clear indication to consult a diabetes specialist. When a patient has developed advanced complications, a diabetes specialist cannot be expected to be able to lessen the burden of these complications.