HYPOGLYCEMIA

reduction of the concentration of glucose in the blood serum below normal levels, commonly occurring as a complication of treatment for diabetes mellitus. Even brief falls in serum glucose levels can produce severe brain dysfunction. In healthy individuals, an intricate glucoregulatory system acts rapidly to counter hypoglycemia by reducing insulin production (insulin is important in the mechanism that removes glucose from the bloodstream) and mobilizing energy reserves from the fat and liver. When this regulatory system does not operate, as in insulin-dependent diabetics, disproportionately large amounts of insulin in the blood result in sudden drastic falls in circulating glucose. Fasting hypoglycemia can be a life-threatening problem; it occurs most often in diabetic patients who have accidentally overdosed on insulin by mistiming their therapy, missing meals, or exercising without compensating for increased glucose use. The condition also occurs in otherwise healthy individuals with insulin-producing tumours or as a late complication of starvation or other metabolic disorders. The symptoms of hypoglycemia result from energy starvation in the central nervous system and include mental impairment, confusion, lethargy, and seizures; in severe cases, hypoglycemia causes coma and death. Diagnosis is based on the concurrence of these neurological symptoms, low levels of circulating glucose, and the alleviation of the patient's symptoms upon the rapid oral or intravenous administration of glucose, which is the usual treatment for the condition.