Diabetes mellitus as presenting feature in extra-adrenal pheochromocytoma: report of a case.

Secondary diabetes mellitus was the main abnormal finding in a young lean woman with benign extra-adrenal para-aortic norepinephrine and dopamine secreting pheochromocytoma. Glucose and insulin response to oral glucose and C-peptide secretion after glucagon i.v. were evaluated before and after alpha-blockade with phenoxybenzamine. Alpha-blocking treatment restored the inhibited basal and stimulated C-secretion but did not normalize glucose tolerance. After tumor removal metabolic abnormalities were normalized, confirming the role of endogenous catecholamine excess in the pathogenesis of our patient's glucose intolerance.