Hypoglycemia, condition characterized by an abnormally low level of sugar in the blood. Symptoms of hypoglycemia include weakness, shakiness, nervousness, anxiety, and faintness and actual fainting. Patients also may show marked personality changes and may seem intoxicated. Hypoglycemia is the result of hyperinsulinism, or an excess of insulin, due either to an overdose of insulin—in the case of persons with diabetes mellitus—or to the body's overproduction of insulin. Insulin is instrumental in regulating carbohydrate metabolism; when hyperinsulinism occurs, glucose is sharply depleted in the process of conversion to glycogen in the liver and muscles and to fat in the adipose tissues.
Reactive, or functional, hypoglycemia—the most common type—occurs particularly among persons under emotional stress. It is also due to overproduction of insulin, commonly three to five hours after meals. Its symptoms are milder than those suffered by insulin-dependent diabetics, and it can be controlled by lowering carbohydrate intake. Because reactive hypoglycemia has many of the classical symptoms of depression or anxiety, it is often wrongly believed to be the cause of underlying psychological disorders. Even when this physical condition is properly diagnosed, it is most often found to be incidental to, rather than the direct cause of, the patient's