Unconsciousness caused by very low blood sugars, usually less than 40 mg/dl. The most common cause is a reaction to insulin or an oral hypoglycemic agent. The patient typically will recognize, after reviving, that coma was preceded by heavy exercise, limited caloric intake, or a recent increase in the dose of diabetic medications. Occasionally alcoholic patients, patients with salicylate overdoses, or severely malnourished patients will present with coma and low blood sugar. Very rarely, the hypoglycemic patient will be found to have an insulin-secreting tumor of the pancreas.