Insulin action in primary hyperaldosteronism before and after surgical or pharmacological treatment

The relationship between arterial hypertension and insulin resistance has l ong been established. We used primary hyperaldosteronism as a model of the relationship between secondary hypertension and insulin sensitivity. Our gr oup consisted of 9 patients with arterial hypertension caused by primary hy peraldosteronism. Five of these patients with aldosterone producing adenoma were operated on and four patients with idiopathic hyperaldosteronism were treated with spironolactone. Hyperinsulinaemic euglycaemic clamp technique was performed before and at least 6 months following the treatment to eval uate the insulin action. Significantly lower glucose disposal rate (M), ins ulin sensitivity index (M/I) and decreased metabolic clearance rate of gluc ose (MCRG) were found in patients before treatment as compared to healthy c ontrols. In both treated groups the blood pressure and plasma potassium con centrations returned to normal values, whereas plasma aldosterone levels we re normalised only after surgical removal of the adenoma. Significantly imp roved insulin action (M/I: 30.2 +/- 5.9 vs. 51.4 +/- 12.2 mu mol.kg(-1).min (-1) per mU.l(-1) x 100, p = 0.017) was observed in patients after operatio n of aldosterone producing adenoma. In contrast, spironolactone treatment o f patients with idiopathic hyperaldosteronism did not significantly influen ce insulin action (Mn: 24.5 +/- 7.3 vs. 18.7 +/- 7.6 mu mol.kg(-1).min(-1) per mU.l(-1) X 100, p = 0.198). Since plasma aldosterone concentrations hav e been normalised only in patients after removal of the adenoma whereas the y remained increased in spironolactone treated group, we suppose that aldos terone itself could play a role in the development of impaired insulin acti on.