A Case of Improved Diabetes Mellitus After Removal of Nonfunctioning Adrenal Incidentaloma Diagnosed as Pheochromocytoma

Pheochromocytoma not only decreases insulin secretion but also increases insulin resistance. One third of patients with pheochromocytoma have diabetes mellitus and their clinical prognosis showed improvement after surgery. Until now, those patients whose prognosis for diabetes mellitus improved after the operation of pheochromocytoma had typical characteristics such as hypertension, palpitation, headache and elevated hormones such as Vanillylmandelic acid, metanephrine, epinephrine and norepinephrine. We present the case of a 75-year-old woman with asymptomatic adrenal incidentaloma identified as pheochromocytoma which exhibited normal biochemical test results, and after removal of the abdominal mass, her severe hyperglycemia improved.