Insulin resistance in hypertensives: effect of salt sensitivity, renin status and sodium intake

Objective Homeostasis Model Assessment (HOMA index) is predictive of insuli n sensitivity in normal and diabetic patients. This study was designed to s ee if insulin resistance in hypertensives, measured using the HOMA index, d iffers, based on salt sensitivity, renin status and sodium intake. Methods Fasting insulin and glucose were determined in subsets of 426 essen tial hypertensives, and normotensives, HOMA was calculated as fasting gluco se (mmol) x fasting insulin (muU/ml)/22.5. Results Four hundred and twenty-six essential hypertensives and normotensiv es from four HERMES centers form the basis of this report, There was no dif ference in the HOMA index between hypertensives and normotensives (P = 0.29 1) or between hypertensives grouped according to blood pressure salt sensit ivity (P = 0.153), However, when essential hypertensives were subgrouped by renin status, the low-renin group had significantly lower (P < 0.01) HOMA index than the normal/high-renin group, When normal/high-renin group was di vided into modulators and non-modulators, the non-modulators had significan tly higher HOMA index (P < 0.001) than other hypertensive subsets. The effe ct of sodium intake on the HOMA index was significant only for non-modulato rs (P < 0.002), with salt restriction increasing insulin resistance. Conclusion Insulin sensitivity differs among subsets of essential hypertens ion, non-modulators being most insulin resistant and the low-renin subset i nsulin sensitive. Salt restriction might have an adverse effect on insulin sensitivity in non-modulators, The reduction in cardiovascular risk seen in low-renin hypertensives may be related to their increased insulin sensitiv ity; in contrast, the clustering of cardiovascular risk factors seen in non -modulators may be due to increased insulin resistance. (C) 2001 Lippincott Williams & Wilkins.