Hypoglycemia in adults: Clinical manifestations, definition, and causes
- F John Service, MD, PhD
F John Service, MD, PhD
- Emeritus Professor of Medicine
- Mayo Clinic College of Medicine
- Philip E Cryer, MD
Philip E Cryer, MD
- Professor of Endocrinology and Metabolism in Medicine
- Washington University in St. Louis
In patients without diabetes, hypoglycemia is a clinical syndrome with diverse causes in which low plasma glucose concentrations lead to symptoms and signs, and there is resolution of the symptoms/signs when the plasma glucose concentration is raised . In patients with diabetes, hypoglycemia is defined as all episodes of an abnormally low plasma glucose concentration (with or without symptoms) that expose the individual to harm . In patients with diabetes, the hypoglycemia symptoms and signs occur as a consequence of therapy. The primary task in a patient without diabetes is to make an accurate diagnosis, whereas the primary task in a patient with diabetes is to alter therapy in an attempt to minimize or eliminate hypoglycemia.
This topic will review the clinical manifestations, definitions, and causes of clinical hypoglycemia. The evaluation of patients with hypoglycemia, detailed information on specific causes, and the management of hypoglycemia in patients with diabetes are reviewed elsewhere. (See "Hypoglycemia in adults without diabetes mellitus: Diagnostic approach" and "Insulinoma" and "Factitious hypoglycemia" and "Nonislet cell tumor hypoglycemia" and "Management of hypoglycemia during treatment of diabetes mellitus".)
Patients who have only sympathoadrenal symptoms (anxiety, weakness, tremor, perspiration, or palpitations) but normal concurrent plasma glucose concentrations have a low probability of having a hypoglycemic disorder. This combination of normal glucose in the face of sympathoadrenal symptoms occurs most commonly in the postprandial state. (See "Postprandial (reactive) hypoglycemia", section on 'Postprandial syndrome'.)
Hypoglycemia is common in type 1 diabetes, especially in patients receiving intensive insulin therapy, in whom the risk of severe hypoglycemia is increased more than threefold in the Diabetes Control and Complications Trial (DCCT). Plasma glucose concentrations may be less than 50 to 60 mg/dL (2.8 to 3.3 mmol/L) as much as 10 percent of the time . Patients with type 1 diabetes may suffer an average of two episodes of symptomatic hypoglycemia per week, thousands of such episodes over a lifetime of diabetes, and one episode of severe, at least temporarily disabling hypoglycemia per year. Severe hypoglycemia events, the most reliable values albeit representing only a small fraction of the total hypoglycemic experience, have been reported to range from 62 to 320 episodes per 100 patient years in type 1 diabetes [1,3,4].
Hypoglycemia is less frequent in type 2 diabetes than it is in type 1 [3,5]. Population-based data indicate that the overall event rate for severe hypoglycemia (requiring the assistance of another individual) in insulin-treated type 2 diabetes is approximately 30 percent of that in type 1 diabetes (35 versus 115 episodes per 100 patient-years)  and that event rates for hypoglycemia requiring professional emergency medical treatment range from 40 to 100 percent of those in type 1 diabetes [7,8].
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- CLINICAL MANIFESTATIONS
- Laboratory findings
- Patients with diabetes
- Patients without diabetes
- DIFFERENTIAL DIAGNOSIS
- CAUSES OF HYPOGLYCEMIA
- Hypoglycemia in diabetes
- Hypoglycemia in patients without diabetes
- - Drugs
- - Critical illness
- - Malnourishment
- - Cortisol deficiency
- - Nonislet cell tumors
- - Endogenous hyperinsulinism
- - Accidental, surreptitious, or malicious hypoglycemia
- INFORMATION FOR PATIENTS