PARADOXICAL ENHANCEMENT OF TOLBUTAMIDE‐INDUCED INSULIN RELEASE BY DIAZOXIDE IN A PATIENT WITH ISLET CELL HYPERPLASIA

A case of islet cell hyperplasia in a ten year old black male with symptomatic fasting hypoglycemia was documented histopathologically. Provocative studies with glucose, tolbutamide, glucagon, and diazoxide were performed to test the insulin response of hyperplastic islets. The islets responded to glucose, glucagon, and tolbutamide. Diazoxide potentiated the tolbutamide-induced insulin response, and this effect of diazoxide was not blocked by propranolol. In the diagnostic work up of islet cell hyperplasia, dizoxide may paradoxically potentiate tolbutamide-induced insulin release, a finding which may falsely suggest progression of the disease.