Insulin-mediated glucose disposal in black south Africans with essential hypertension

We used the hyperinsulinaemic euglycaemic clamp method to assess insulin-mediated glucose disposal in ten black South African patients with newly-diagnosed essential hypertension, compared to ten normotensive controls. The patients were all nonobese with normal glucose tolerance. Comparisons were made before and 12 weeks after treatment with a long-acting ACE inhibitor. The mean glucose disposal (M) and disposal expressed as glucose sensitivity index (M/I) were significantly reduced in the hypertensives vs. controls (M: 6.8 +/- 0.9 vs. 9.7 +/- 0.8 mg/kg/min; MI: 7.1 +/- 1.0 vs. 12.5 +/- 1.7 mg/kg/min/mU/l x 100) (p = 0.03 and 0.01, respectively). Following therapy, M/I increased in the patients to values not significantly different to those of the controls. Insulin resistance is an independent feature of essential hypertension in black South African patients, and is partially corrected by treatment with a long-acting ACE inhibitor.