Tumor resection attenuated the impaired tolerance of glucose in patients with asymptomatic pheochromocytoma.

A 51-year-old male was admitted to our hospital because of glucosuria and an abdominal tumor. While blood pressure levels were maintained within normal ranges, serum adrenaline and noradrenaline levels and the urinary excretion of total metanephrine increased. The oral glucose tolerance test (75g-OGTT) showed a diabetic pattern. Venography and blood sampling from the adrenal vein showed the existence of a right adrenal tumor. Right adrenalectomy normalized serum catecholamine levels and the urinary excretion of metanephrine. Simultaneously, fasting glucose levels returned to normal. The present case suggested that increased metanephrine secretion may affect only pancreatic insulin secretion, but not blood pressure levels in the patient with asymptomatic pheochromocytoma.