Hypoglycemia

Hypoglycemia is an important and easily reversible cause of altered mental status in patients presenting to the emergency department. Hypoglycemia accounts for approximately 7% of patients presenting to the emergency department with an altered mental status. In diabetic patients, approximately 25% will experience hypoglycemia on a regular basis. There is no universally accepted definition, but this condition is generally defined as a blood glucose level < 50-60 mg/dL. Symptoms will vary significantly between patients and the blood glucose level at which a patient become symptomatic is also highly variable.

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Initial Actions and Primary Survey

Hypoglycemia should be considered in the differential diagnosis of all patients with an altered mental status (including the pre-hospital setting). Nowadays, this condition is rapidly identified with bedside glucometers and rapidly treated with intravenous dextrose. A patient presenting with hypoglycemia can easily be misdiagnosed as a stroke, seizure, psychosis, drug ingestion, or a traumatic head injury if the blood glucose level is not obtained. Failure to determine blood glucose levels early in the evaluation process can lead to a missed diagnosis and be associated with progressive CNS dysfunction, cardiac dysrhythmias, or even death. Obtaining an accurate medical history in a patient with an altered mental status can be difficult. Attempts should be made to elicit any history of diabetes, renal or liver failure, alcohol or drug use and to determine an accurate medication list (insulin or oral hypoglycemic agents in diabetics) or any history of new medications. Hypoglycemia may also occur in non diabetic patients with limited glycogen stores (chronic alcoholics, infants and small children) during stress states such as sepsis and can occur in various endocrinopathies such as adrenal insufficiency.

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Differential Diagnosis

Hypoglycemia can mimic a number of neurologic conditions including:

• Coma
• Stroke
• Seizures
• Syncope

In addition, a number of conditions can cause or are associated with hypoglycemia:

• Adrenal insufficiency
• Alcohol abuse (chronic)
• Diabetics (predisposing factors - use of long acting insulin, oral hypoglycemic agents)
• Insulinoma
• Liver disease
• Sepsis

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Classic Presentation

Patients presenting with hypoglycemia may have a wide range of signs and symptoms, however clinically they are divided into 2 broad categories;

1. Neuroglycopenic (mental status)
2. Hyperepinephrinemic (sympathomimetic)

Glucose is the main substrate for CNS function and therefore most hypoglycemic episodes include neurologic dysfunction manifested by:

• Altered level of consciousness
• Agitation/combativeness
• Confusion/lethargy
• Seizures or focal neurologic deficits

As blood glucose levels fall counterregulatory hormones are released (mainly catecholamines) resulting in a "hyperepinephrinemic" state. Findings include;

• anxiety/irritability
• diaphoresis
• nausea/vomiting
• nervousness
• palpitations/tachycardia
• tremor

CNS dysfunction predominates in most cases of hypoglycemia but a rapid drop in blood glucose will also produce the "hyperepinephrinemic" findings to some degree. The typical patient presenting with acute hypoglycemia will have an altered mental status and exhibit tachycardia and diaphoresis.

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Diagnostic Testing

Laboratory testing

Bedside glucose monitoring is the preferred method to obtain blood glucose levels given that results are immediately available. The accuracy of bedside glucose testing is less reliable at extremely high and low glucose levels so these values may need confirmation by sending a blood specimen to the laboratory for a basic metabolic profile.

Treatment

Any patient presenting with an altered mental status and a blood glucose level < 60 mg/dL should be treatment for hypoglycemia. Glucose (dextrose) should be administered based on a patients clinical symptoms and should not wait for diagnostic confirmation of hypoglycemia. Oral: Oral glucose is the best when it can be given safely in awake and alert patients. In adults a total of 300g (1200cal) of carbohydrate should be given (soda, juice, sandwich, snacks), complex carbohydrates will be better at maintaining blood glucose levels. Intravenous Glucose: In adults start with 50 ml of 50% Dextrose in Water (D50). In pediatric patients use 1 ml/kg of 25% Dextrose in water or 2-4 ml/kg of 10% Dextrose in water. Monitor mental status and blood glucose measurements every 15-30 min after glucose administration. Persistent hypoglycemia may require additional boluses or continuous infusions of glucose. Remember to consider giving thiamine to alcoholic patients to prevent Wernicke's Encephalopathy. Intravenous glucose is typically administered to the patient with profound hypoglycemia with an altered mental status of those with significant signs and symptoms. Glucagon: Can be used when there is no IV access. In adults administer 1 mg IM and 0.5 mg in pediatric patients < 20 kg . In conditions with depleted glycogen stores (elderly, alcoholic) glucagon may not be effective. Octreotide: May be useful in the setting of sulfonylurea-induced hypoglycemia not responsive to other therapies. Initial dose of 50-125 ug subcutaneously.

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Disposition

Discharge criteria for patients following a symptomatic episode of hypoglycemia:

• Brief episode
• Full neurologic recovery
• Able to eat
• No major co-morbid conditions that require hospital admission
• Cause of the episode identified and addressed
• Treatment plan to prevent future episodes understood by the patient
• Hypoglycemia accidental
• Relapse unlikely (no long-acting insulin or oral agents, nor prolonged excretion or metabolism)
• Ability to do home glucose monitoring
• Responsible person able to be with the patient
• Follow-up arranged

Admission criteria for patients following an episode of hypoglycemia:

• Cause of hypoglycemia due to long acting insulin or oral agents (the Sulfonylurea class of diabetic medications are well known to produce hypoglycemic states)
• No obvious cause
• Persistent neurologic deficits
• Persistent or recurrent hypoglycemic episodes in the ED

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Pearls and Pitfalls

• Failure to consider hypoglycemia in the work-up of a patient presenting with altered mental status can lead to a misdiagnosis or a delay in diagnosis.
• Administer glucose based on clinical presentation if a bedside glucometer is unavailable and laboratory confirmation will delay treatment.
• Feed patients following a response to IV glucose if they are able to eat.
• Use glucagon in symptomatic hypoglycemic patients who are unable to take oral glucose and whom have no IV access
• Strongly consider admitting patients who are on long-acting insulin or oral hypoglycemic agents.
  

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References

1. Smeeks FC. Hypoglycemia. Available on emedicine at; http://emedicine.medscape.com/article/767359-overview. Accessed June 16, 2010.