Hypoglycemia associated with a leiomyosarcoma of the small bowel

A patient with recurrent hypoglycemic episodes associated with a leiomyosarcoma of the small bowel is described. Fasting plasma insulin levels were consistently low and a subnormal insulin response to provocative stimuli (oral glucose and i.v. glucagon) was shown. After removal of the tumor, hypoglycemic episodes disappeared, fasting plasma insulin concentrations rose to normal values and insulin response to both OGTT and glucagon test was markedly enhanced. The possible mechanisms responsible for the hypoglycemia and the causes of subnormal insulin response to provocative stimuli are discussed.