Insulin sensitivity and beta-cell function in essential hypertension and normotensive first-degree relatives of hypertensive subjects.

We investigated glucose metabolism and beta-cell function in normotensive subjects with one essential-hypertensive parent and in subjects with mild/moderate essential hypertension (eHT) before and after 12-week treatment with nitrendipine. The hypertensive-parent group comprised 12 normotensive subjects, and the hypertensive group 15 subjects with mild/moderate eHT. A corresponding control group composed of 20 normotensive subjects was also investigated. All subjects underwent a frequently sampled intravenous glucose tolerance test (FSIGT). Hypertensive subjects underwent FSIGT testing before and after 12 weeks of treatment with nitrendipine (20 mg per day). Insulin sensitivity, glucose effectiveness and beta-cell function were investigated using the minimal model technique on the basis of FSIGT test data. No significant differences were detected in any of the minimal-model parameters either between the hypertensive-parent group and the control, or between the hypertensive group (before nitrendipine treatment) and the control. Twelve weeks of anti-hypertensive treatment with nitrendipine led to an increase in glucose effectiveness and a non-significant increase in glucose tolerance, but had no significant effects on other minimal-model parameters or on the serum lipid profile. Our results suggest that eHT cannot be considered consistently associated with insulin resistance. Nitrendipine treatment appears to have no undesirable effects on peripheral sensitivity to insulin or on beta-cell function. However, the 12-week course led to a 72% increase in glucose effectiveness.