Endocrine Abstracts

Context: Primary aldosteronism (PA) represents the most frequent cause of a curable secondary arterial hypertension. Conflicting data have been published regarding the effect of aldosterone excess on glucose and lipid metabolism.

Objective: Our aim was to analyze insulin sensitivity and beta cell function in a cohort of PA patients. Prospective follow-up investigations were performed in a subgroup of patients before and after adrenalectomy to assess the metabolic outcome.

Design: Oral glucose tolerance test, combined intravenous glucose tolerance test (ivGTT) - hyperinsulinaemic-euglycaemic glucose clamp test and arginine test were carried out after a 12-h fasting period.

Patients: Twenty two consecutive PA patients with both unilateral (n=14) and bilateral (n=8) disease were recruited through the Munich center of the German Conn’s Registry. The control group of EH patients (n=11) of corresponding age, gender and BMI were recruited from our hypertension unit. A normotensive cohort (n=11) was recruited as control group.

Results: At baseline, first phase insulin reaction in ivGTT was significantly reduced in patients with PA as compared to normal controls (36.0 (24.0; 58.7) vs 90.1 (52.6; 143.8) μU/ml, P=0.031) and lower in comparison to EH without reaching statistical significance (53.2 (30.8; 73.3) μU/ml, P=0.123). The study was repeated 6 months afterunilateral adrenalectomy in 9 consecutive patients with APA.At this time point, blood pressure was normalized in the majority of patients while BMI remained unchanged (26.9 (25.5; 37.6) vs 27.5 (25.1; 35.6) kg/m², P=0.401).The first phase insulin reaction in response to glucose significantly increased at follow-up (from 36.0 (25.5; 58.7) to 48.5 (30.4; 95.2) μU/ml, P=0.038). In contrast, insulin sensitivity, insulin resistance and response to i.v. arginine did not differ before and after adrenalectomy.

Conclusion: These findings provide evidence that aldosterone excess has a direct negative effect on beta cell function in patients with PA. Accordingly, following adrenalectomy, early insulin secretion improves significantly in these patients.