Phaeochromocytoma and diabetes mellitus: further evidence that alpha 2 receptors inhibit insulin release in man.

An insulin-dependent diabetic presenting with thirst, polyuria and weight loss was noted to be hypertensive and shown subsequently to have a right adrenal phaeochromocytoma. Pre-operative control of both diabetes and hypertension was achieved with propranolol and phenoxybenzamine, but not with propranolol alone. Full recovery with restoration of normal glucose tolerance and blood pressure followed successful surgery. Analysis of this patient's response to medical therapy provides further evidence that alpha 2 receptors inhibit insulin release in man. Since as many as one-third of phaeochromocytomas are not detected during life, this diagnosis should be considered as an uncommon cause of carbohydrate intolerance in patients with diabetes mellitus, especially if accompanied by continuous or paroxysmal hypertension.