[Comparative effects of captopril and chlorthalidone on glucose tolerance and insulin levels essential hypertensives].

PURPOSE

To compare the effects of chlortalidone (CL) and captopril (Cp) upon glucose tolerance and serum insulin levels in essential hypertensive patients.

METHODS

Non obese essential hypertensive patients with normal glucose tolerance test (OGTT) and diastolic blood pressure (DBP) > 90 mmHg and < or = 115 mmHg in the seated position were treated, in a randomized fashion, with Cp or CL during 16 weeks, after 16 weeks of placebo. The OGTT was performed after placebo and after active therapy, with serum insulin levels determinations carried out before and 120 minutes after oral glucose load.

RESULTS

Twenty four patients in the CL group and 19 in the Cp concluded the study. Hypocalemia (serum potassium < 3.8mEq/L or serum potassium reductions > or = 0.9mEq/ L) occurred in nine patients of the CL group (CL H). In this group CL therapy induced increments in the area under the curve of glycemia during OGTT (582 vs 610mg/h/dL, p < 0.05) that were not observed in the normocalemic patients of the CL (CLN) or Cp groups. Serum insulin levels during OGTT did not change with active therapy in all three groups. The insulin sensitivity index, however, decreased significantly in the CLH (1.9 vs 1.4; p < 0.05) and CLN (10.1 vs 4.3, p < 0.05) but remained unchanged in the Cp group (3.1 vs 2.5; NS). The insulin response to glucose index increased in the Cp (0.28 vs 0.40; p < 0.05) group but not in the CLH (0.25 vs 0.42; NS) and CLN (0.07 vs 0.24).

CONCLUSION

The antihypertensive therapy with chlortalidone in essential hypertensive patients may result in reductions in the peripheral sensitivity to insulin that can be accompanied by increases in glycemic levels after oral glucose load, particularly in patients who develop hypocalemia. Our results indicate that Cp therapy induces increments in insulin response to glucose without detectable changes in peripheral insulin sensitivity.