Prevalence and progression of carbohydrate disorders in patients with pheochromocytoma/paraganglioma: retrospective single-center study.

Carbohydrate disorders are the most frequent metabolic disorders, affecting a significant proportion of patients with pheochromocytoma.A retrospective study assessed the prevalence and progression of carbohydrate disorders in 204 patients (92 men, 112 women) with histologically proven pheochromocytoma diagnosed in a single specialized tertiary center during a 40-year period (1978-2017). One hundred were followed-up after tumor removal.Carbohydrate disorders were diagnosed in 49.5% of cases: 30.4% with diabetes and, 19.1% prediabetes. Subjects with carbohydrate disorders had significantly greater age at diagnosis and higher 24-hour urine metanephrine and normetanephrine concentrations than those with normal glucose tolerance. One-third of patients with diabetes achieved good glycemic control under oral treatment (54% on metformin monotherapy). One-third of patients overall required preoperative insulin treatment. Postoperative follow-up (100 patients; 5-year mean duration) showed reduced prevalence of diabetes (13% vs. 33%; P=0.0007) and prediabetes (12% vs. 24%; P=0.027). Almost 60% of subjects initially diagnosed with carbohydrate disorders recovered normal glucose tolerance after surgery; these subjects had significantly higher preoperative urine metanephrine/normetanephrine levels than those with persistent diabetes/prediabetes. Correlation analysis revealed a moderate negative relationship between urine metanephrine/normetanephrine concentration and the outcome of the carbohydrate disorders (Spearmen's Rho=-0.507; P=0.013). There was no significant difference according to pre- or postoperative prevalence of obesity (15% vs. 16%; P=0.845) or dyslipidemia (46% vs. 39%; P=0.316).Carbohydrate disorders affect approximately 50% of pheochromocytoma patients; 30% develop overt diabetes, which may be the only clinical manifestation in some rare cases. Pheochromocytoma-related diabetes is more likely to affect patients with predominant adrenaline secretion. It is often easy to control and usually requires oral antidiabetic treatment. Reversibility of carbohydrate disorders depend on severity, preoperative metanephrine level, age and weight.