The Study on the Insulin Sensitivity and the Effects of Hyperinsulinemia on the Renal Function and Pressor Systems in Patients with Primary Aldosteronism

To clarify insulin sensitivity and roles of insulin in the pathophysiology of primary aldosteronism, insulin sensitivity was measured using the euglycemic hyperinsulinemic glucose clamp technique and insulin release during the 75g oral glucose tolerance test (OGTT) in patients with primary aldosteronism. Eight patients with that disease (PA; 53.1±2.8 years, mean ± SEM) and 14 normotensive subjects (NT; 53.7±2.5 years) were employed in this study. The 2-hour euglycemic hyperinsulinemic glucose clamp technique was performed in the 8 PA before adrenalectomy, 7 PA after adrenalectomy and 14 NT. The mean rate of glucose infusion to maintain euglycemia for the last 30 minutes of the clamp technique was used as an indicator of insulin sensitivity (M-value). Blood and urine samples were collected before and at the end of 2-hour hyperinsulinemia to measure the parameters described below. There was no significant difference between the two groups in fasting blood sugar and plasma insulin level. The total blood sugar level during the OGTT (area under the curves) (ΣBS) was significantly higher in PA than in NT, and the total insulin level during the OGTT (area under the curves) (ΣRI) was significantly lower in PA than in NT. In PA after adrenalectomy, ΣBS was significantly decreased and ΣIRI was significantly increased in comparison to the normal range. In PA, a significant positive correlation (p