Hypoglycemia

Except in diabetic patients receiving insulin or sulfonylureas, hypoglycemia is a rare disorder. It is identified by modified Whipple's criteria consisting of neuroglycopenic symptoms, a blood glucose level equal to or less than 40 mg/dL, and relief of symptoms by glucose use. The sources of the body glucose are dietary intake, glycogenolysis, and [figure: see text] gluconeogenesis. The metabolism of glucose involves oxidation and storage as glycogen or fat. Causes of hypoglycemia include medications or toxins capable of decreasing blood glucose, disorders associated with fasting hypoglycemia, and postprandial hypoglycemic disorders. The most common type of hypoglycemia is insulin-induced hypoglycemia in diabetics. Insulinoma is rare; however, it is the most common hormone-secreting islet cell tumor. The diagnosis is made by the occurrence of hypoglycemia in the presence of symptoms of neuroglycopenia and inappropriately high levels of insulin and C-peptide. In hospitalized patients, the diagnosis is best made by prolonged fast. Most insulinomas are small and require invasive methods for precise localization. In surreptitious insulin use, hypoglycemia is associated with low plasma C-peptide. Postprandial hypoglycemia occurs in response to feeding and is generally caused by excessive insulin effect. It is seen in patients with postgastric surgery and rarely in early diabetes mellitus. Idiopathic postprandial hypoglycemia is rare and seems to be caused by subtle abnormalities of insulin response to food. Treatment of postprandial hypoglycemia consists of frequent small meals, with deletion of refined carbohydrate and increased protein intake. Primary treatment of insulinoma is surgical resection of the tumor.