Effects of selective alfa 1 and beta 1-adrenoreceptor blockade on lipoprotein and carbohydrate metabolism in hypertensive subjects, with special emphasis on insulin sensitivity.

The central role of insulin resistance in patients with essential hypertension was the impetus for the present study, in which carbohydrate and lipid metabolism were examined before and after three months treatment with doxazosin (n = 14) and atenolol (n = 15). After completion of a randomised parallel group trial, the study was extended in a subgroup of the patients who continued treatment with doxazosin for a further nine months (n = 18). Insulin sensitivity was measured with the euglycemic hyperinsulinaemic clamp. Blood glucose and plasma insulin were analysed in the fasting state and during an intravenous glucose tolerance test (IVGTT). Lipoprotein fractions were analysed in serum. After three months, SBP and DBP in the standing position decreased to the same extent after the two drugs whereas the decrease in supine SBP did not reach statistical significance in the doxazosin group. Doxazosin, in contrast to atenolol, decreased serum triglycerides (-17%, P < 0.04) by lowering the VLDL and LDL fractions. Serum cholesterol fell after doxazosin (-7%, P < 0.02) but not after atenolol. The effects of doxazosin on serum lipids remained the same during the long-term follow-up. At three months neither drug had significantly affected variables reflecting insulin sensitivity although atenolol tended to decrease the insulin sensitivity index (-17%, P = 0.08). After 12 months the doxazosin group showed a significant increase in the insulin sensitivity index and a significant decrease in both basal plasma insulin and in the late insulin response at IVGTT.(ABSTRACT TRUNCATED AT 250 WORDS)