Acute Hypoglycemia

Updated: Sep 09, 2020
Author: Frank C Smeeks, III, MD; Chief Editor: Erik D Schraga, MD 

Practice Essentials

Hypoglycemia is defined according to the following serum glucose levels:

  • < 50 mg/dL in men

  • < 45 mg/dL in women

  • < 40 mg/dL in infants and children

Treatment and disposition of hypoglycemia are guided by the history and the clinical picture. Serum glucose levels should be measured frequently and used to guide treatment, because clinical appearance alone may not reflect the seriousness of the situation.[1]



If the cause of hypoglycemia is other than oral hypoglycemic agents or insulin in a diabetic patient, additional laboratory tests may be necessary.

In a cross-sectional study of 291 adults presenting to the emergency department (ED) with hypoglycemia (≤ 60 mg/dL) or altered mental status resolved by glucagon or glucose, Sinert et al determined that routine laboratory testing is justified in patients presenting to the ED with hypoglycemia, because of the high rate of abnormal laboratory results.[2]  Of the 291 patients, 200 (69%) had at least 1 laboratory abnormality, including newly diagnosed (23%) or preexisting (32%) renal failure, hypokalemia (8%), hyperkalemia (11%), leukocytosis (4.2%), and pyuria (19%).

A retrospective study by Lipska et al on trends in US hospital admissions for hyperglycemia and hypoglycemia from 1999 to 2011 that included 279,937 patients found that the rates of admissions for hyperglycemia decreased from 114 to 70 admissions per 100,000 while admissions for hypoglycemia increased from 94 to 105 admissions per 100,000. Hypoglycemia rates were also 2 times higher for patients aged 85 years or older, and admission rates for both hyperglycemia and hypoglycemia were 4 times higher for Black patients.[3]

In a cohort study of 201,705 adults with diabetes, patients who were at greatest risk for an episode of hypoglycemia requiring an ED visit or hospitalization were those with type 1 diabetes mellitus, multiple comorbidities, prior severe hypoglycemia, or sulfonylurea or insulin use.[1]  



Treatment of hypoglycemia consists of correcting the glucose deficiency and directing further treatment to the underlying cause.[4, 5, 6, 7, 8, 9]

Consultation is guided generally by determination of the underlying cause of hypoglycemia. Endocrinology, toxicology, or infectious disease subspecialists may be consulted, but, in general, an internal medicine or family practice specialist can manage hypoglycemia and determine its underlying etiology.

Prehospital care

Emergency medical services (EMS) care generally consists of drawing serum glucose or using Accu-Chek prior to administering dextrose 50% in water (D50) in the field. This procedure usually is performed in the case of an unconscious patient or a patient with altered mental status.

Many advanced cardiac life support (ACLS)-trained and first responders are able to perform simple bedside glucose testing. This procedure should be part of the normal protocol for any EMS unit.

When hypoglycemia is found and treated in the diabetic patient, the patient may awaken and not desire transport. In view of the multiple causes of a sudden episode of hypoglycemia in a patient with previously well-controlled diabetes, it is prudent to advise transport and emergency department (ED) evaluation.[10, 11]

Emergency department care

The initial approach in the ED should include the following:

  • ABCs (airway, breathing, circulation)

  • Intravenous (IV) access

  • Oxygen

  • Monitoring

  • Accu-Chek

Administration of glucose as part of the initial evaluation of altered mental status often corrects hypoglycemia. As is the case in the field, treatment should not be withheld while one is waiting for a laboratory glucose value. Because the brain uses glucose as its primary energy source, neuronal damage may occur if treatment of hypoglycemia is delayed.

A hyperglycemic patient with an altered mental status may receive a bolus of glucose. This procedure is unlikely to harm the patient with high glucose; however, the delay in giving glucose to the hypoglycemic patient may be detrimental.

If an Accu-Chek can be performed immediately, it is reasonable to await the results (which are typically available within 1 minute) before deciding whether to administer glucose.

Once the diagnosis of hypoglycemia is made, search carefully for the cause in the previously healthy patient. In the diabetic patient, potential causes of the hypoglycemic episode include medication changes, dietary changes, new metabolic changes, recent illness, and occult infection.

A study by Akirov et al found that spontaneous or insulin-related hypoglycemia is associated with increased mortality in hospitalized patients in both the short and long term. The cohort included 33,675 patients who were classified into 6 groups: non–insulin-treated (NITC) and insulin-treated controls (ITC), insulin-related hypoglycemia (IH) or severe hypoglycemia (ISH), and non–insulin-related hypoglycemia (NIH) and severe hypoglycemia (NISH). Hypoglycemia was defined as a blood glucose level of < 70 mg/dL. The mortality risk more than doubled in patients who had NIH and IH (IH [2.2, 2.5]) and approximately quadrupled in patients with NISH and ISH (ISH [4.2, 3.8]).[12, 13]

Admission criteria

Admission criteria for patients with acute hypoglycemia include the following:

  • No obvious cause

  • Oral hypoglycemic agent

  • Long-acting insulin

  • Persistent neurologic deficits

Patients with no known cause or no previous episodes of hypoglycemia must be admitted for further evaluation.

For overdose, accidental ingestion, or therapeutic misadventures with oral hypoglycemics, little correlation exists between the amount of oral hypoglycemic agent ingested and the length or depth of coma. These patients require admission.

Inadequate data are available to predict the extent or the time course of hypoglycemia in children.

Chlorpropamide has demonstrated refractory hypoglycemia for up to 6 days after ingestion. Asymptomatic patients who have ingested hypoglycemic agents should be observed for the development of hypoglycemia, because the onset of action and the half-life are extremely variable. The length of observation is based on the ingested agent.

A small pilot study by Belfort-DeAguiar et al found that inhalation of the beta-2 adrenergic receptor (AR) agonist formoterol may be effective in the prevention or treatment of acute hypoglycemia in patients with type 1 diabetes. Further studies are needed to confirm these results and long-term effects.[14, 15]

Goh et al, using criteria of successful discharge of patients from the observational ward within 24 hours and the hypoglycemia recurrence after discharge, found that selected patients can be treated effectively and safely in a 24-hour observational ward.[16] Of the 203 patients enrolled in the study, 170 were discharged, after meeting a strict set of criteria, and 33 were transferred for inpatient care. The median length of stay in the observational ward was 23 hours.

Patients were contacted at 7 and 28 days after discharge.[16] Of 151 patients contacted, 6 had recurrent hypoglycemia symptoms, 2 of whom returned to the ED and were admitted; 4 patients had mild symptoms self-managed at home.[8] Two other patients returned to the ED for conditions not related to hypoglycemia. Nineteen patients could not be contacted, but no record of a return to the ED could be found.

Discharge criteria

For patients on either short-acting insulin or hypoglycemic agents who have not eaten and have had their hypoglycemia reversed rapidly, a high carbohydrate meal prior to discharge is recommended. Discharge may be considered after a high carbohydrate meal in the following situations:

  • An obvious cause is found and treated

  • The hypoglycemic episode is reversed rapidly

A competent adult who has been directed to monitor fingerstick glucose measurements closely during the remainder of the day should accompany the patient after discharge.

Discharging a patient following a hypoglycemic episode that is likely the result of a long-acting oral hypoglycemic medication is a potential pitfall. Any patient for whom the cause is not identified readily may have a recurrence of hypoglycemia with resultant sequelae.

Patient education

Patients must be counseled as to the causes and the early signs and symptoms of hypoglycemia. This counseling is particularly important for those patients who have a history of prior episodes of hypoglycemia or who have newly diagnosed diabetes. General outpatient diabetic education or inpatient diabetic teaching is indicated.


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