PS 14-74 EVALUATION OF INSULIN SENSITIVITY AND SECRETION IN PRIMARY ALDOSTERONISM

Abstract

Objective: Primary aldosteronism (PA) is a clinical syndrome characterized by hypokalemia, hypertension, and impaired glucose tolerance. Diabetes in PA is characterized by the impairment of both insulin secretion and sensitivity, but the degree of contribution of these two factors is varied. Therefore, we evaluated insulin sensitivity and secretion in patients with PA using homeostasis model assessment (HOMA) and the insulinogenic index (IGI). Design and Method: We analyzed 32 patients with PA. OGTT was performed before adrenalectomy in all patients, and also after the surgery in a subset of patients. Indices for insulin action, evaluated by HOMA, QUICKI and IGI, were calculated and were compared to those of essential hypertensive (EH) patients. Results: EH group consisted of 21 EH patients. Several parameters, such as age, BMI and blood pressure, were matched between PA and EH groups. Fasting glucose and plasma insulin levels of PA patients were higher than those of EH patients. In addition, PA patients had significantly higher stimulated plasma glucose levels after 120 min and lower plasma insulin levels after 30 min compared to EH patients. Insulin sensitivity was more impaired in patients with PA compared to EH patients, and IGI in PA patients was significantly lower than that of EH patients. On the other hand, HOMA-β was similar between PA and EH patients. Serum potassium correlated inversely with HOMA-IR and positively with QUICKI in PA patients. In 5 PA patients, OGTT was performed after unilateral adrenalectomy. In these patients, serum potassium level was normalized and HOMA-IR was significantly improved after operation. Conclusions: Insulin actions in patients with PA was characterized by insulin resistance associated with hypokalemia in addition to the impairment of early-phase secretory response to glucose. Therapeutic intervention aimed at correcting both potassium and aldosterone levels might improve insulin actions in patients with PA.