Diabetes as a marker of pheochromocytoma in hypertensive patients.

OBJECTIVE: To assess the prevalence of diabetes in patients with pheochromocytoma and the probability of pheochromocytoma occurring in hypertensive patients with or without diabetes.

SETTING: A tertiary, referral hypertension department.

PATIENTS AND METHODS: We compared age, body mass index and the frequency of diabetes in 191 patients with pheochromocytoma and a random sample of 880 patients with essential hypertension. Diabetes was defined as current antihyperglycemic treatment or two fasting blood glucose concentrations >or= 7 mmol/l. For patients with pheochromocytoma, we also recorded plasma catecholamine concentrations, the urinary excretion of metanephrines, and tumor characteristics.

RESULTS: Diabetes was present in 68 (35.6%) patients with pheochromocytoma and 192 (21.8%) patients with essential hypertension (P < 0.001). Pheochromocytoma patients with or without diabetes did not differ in body mass index, plasma noradrenaline concentration, metanephrine excretion or tumor characteristics. Age, duration of hypertension and plasma adrenaline concentration were significantly and independently associated with diabetes in patients with pheochromocytoma. They were younger, more likely to be female and had a lower body mass index than those with essential hypertension (P < 0.01). After adjustment for these three variables, the odds ratio for pheochromocytoma in hypertensive patients with diabetes was 5.5 (95% confidence interval, 3.5-8.7). For patients younger than the age of 51 years with a body mass index < 25 kg/m2, the odds ratio was 18.9 (95% confidence interval, 5.9-58.8).

CONCLUSION: Diabetes is present in one in three patients with pheochromocytoma. In young patients with hypertension and normal body weight, the presence of diabetes is a clinical clue to the diagnosis of pheochromocytoma.