The mechanism of pheochromocytoma-induced diabetes is related to insulin resistance and suppression caused by excess catecholamines.2 Through activation of hepatocyte β and α receptors, inhibition of insulin secretion in β cells of the pancreas, and blockade of GLUT4 transporters in muscle and adipose, catecholamines secreted in pheochromocytomas increase glycogenolysis and gluconeogenesis while interfering with normal feedback control of insulin.3 This evidence concerns the gene INS and hereditary pheochromocytoma-paraganglioma.