The clinical diagnosis of insulinoma rests on the demonstration of VVhipple's triad (symptoms of hypoglycemia, low circulating glucose and prompt relief of symptoms after glucose administration). Biochemically, the association of an increased value of immunoreactivc insulin with a low glucose value is diagnostic of insulin-mediated hypoglycemia. Angiographie localization of these tumors is accomplished in more than 90% of cases. The pathologic changes are usually due to a single adenoma, for which surgical cnucleation is the procedure of choice. Malignancy and persistent hypoglycemia occur in slightly less than 10% of cases and can be fairly successfully managed by diazoxide and streptozotocin.