Hypoglycemia is defined as the occurrence of a wide variety of symptoms in association with a plasma glucose level of 40 mg/dL or less. The conditions associated with hypoglycemia in hospitalized patients include exogenous insulin administration, ethanol, drugs (especially chlorpropamide), renal insufficiency, liver disease, infections, total parenteral nutrition, treatment of hyperkalemia with insulin, extensive burns, neoplasia, pregnancy, and a wide variety of less common causes. Although clinical features are helpful in making a diagnosis, a significant proportion of the patients are either asymptomatic or present with symptoms of altered mental status. The diagnosis of hypoglycemia should be considered in all hospitalized patients presenting with adrenergic or neuroglycopenic symptoms and signs suggestive of hypoglycemia. A detailed history along with a physical examination and appropriate laboratory investigations usually identify the specific cause of the hypoglycemia. An episode of hypoglycemia, especially if severe, should be treated with prolonged intravenous infusion of glucose. Prompt recognition and management of hypoglycemia are necessary to prevent significant morbidity and mortality.