The Somogyi Phenomenon: Sacred Cow or Bull?

Posthypoglycemic hyperglycemia (Somogyi phenomenon) occurs infrequently in insulin-treated diabetic patients. When it occurs it is often in children and adolescents, or patients with a short duration of diabetes. Marked hyperglycemia (>220 mg/dL) after hypoglycemia results from a large meal to relieve the symptoms of hypoglycemia. Posthypoglycemic hyperglycemia correlates with falling plasma insulin levels, rather than increasing concentrations of counterregulatory hormones, whose secretion may be defective. Asymptomatic nocturnal hypoglycemia is common but subsequent fasting hyperglycemia is not necessarily the result of “rebound.” More likely, fasting hyperglycemia is due to a falling predawn insulin level. Nocturnal hypoglycemia is dealt with by a readjustment in the timing and dose of insulin. The failure of the Somogyi phenomenon to occur puts insulindependent diabetic patients at increased risk to potential lethal consequences of nocturnal hypoglycemia.