Renovascular hypertension and insulin sensitivity

We tested the hypothesis that the status of the renin-angiotensin-aldosterone system affects insulin sensitivity. Insulin sensitivity (by the euglycaemic insulin clamp technique) was measured in eight patients with angiographically proven renovascular hypertension and in eight normotensive subjects matched for age, gender, body mass index and glucose tolerance. In the patients, insulin sensitivity was measured both at baseline and following 7 days of ACE inhibition. Following glucose ingestion, patients and controls showed similar insulin and glucose responses. Insulin infusion (7 pmol min -1 kg -1 ) promoted similar glucose utilization in the hypertensives and normotensives : 24.8 ± 2.3 vs. 26.0 ± 3.0 μmol min -1 kg -1 respectively. One week of ACE inhibition caused a 20±4 mmHg decrease in mean blood pressure and a 20 ± 6% decrease in peripheral vascular resistance. Plasma angiotensin II concentrations dropped from 24.6 ± 6.3 to 13.5 ± 5.0 pg mL -1 (P < 0.05) and plasma aldosterone from 17 ± 4 to 9 ± 2 ng dL -1 (P < 0.05), and plasma renin activity doubled (from 1.6±0.3 to 3.4±1.7 ng mL -1 h -1 , P<0.02). Nevertheless, insulin sensitivity was unchanged (before, 24.8±2.3 ; after, 25.8±2.2 μmol min -1 kg -1 , P = Ns). During insulin infusion, forearm blood flow did not change from baseline in either set of studies. Also, the antinatriuretic (before, -26 ± 18 ; after, -22±14%) and antikaliuretic (before : -36±13%, after : -39±11%) action of the hormone was unaffected by the therapy. In conclusion, human renovascular hypertension is not associated with insulin resistance. Furthermore, a selective, drastic reduction of the renin-angiotensin-aldosterone system activity and vascular tone does not alter insulin action on glucose and electrolyte metabolism.