Doxazosin improves insulin sensitivity in hypertensive patients.

Insulin sensitivity in terms of glucose disposal rate was measured by the hyperinsulinemic/euglycemic clamp technique in 10 hypertensive patients and 7 normotensive control subjects before and after 12 weeks of doxazosin therapy. Supine blood pressure fell significantly, from 150/98 mmHg before treatment to 136/90 mmHg after treatment (systolic P < 0.001/diastolic P < 0.01). The average dose of doxazosin at the end of the study was 3.3 +/- 0.4 mg/day. The glucose disposal rate during the last 30 minutes of the glucose clamp procedure was significantly increased, from 5.8 +/- 0.7 mg/kg/min before to 7.8 +/- 0.7 mg/kg/min after treatment (P < 0.02). Insulin sensitivity was 8.7 +/- 0.4 mg/kg/min in the normotensive subjects, which represented a significant difference when compared with that of the hypertensive subjects before treatment (P < 0.01). Steady-state serum insulin concentrations, as measured during the glucose clamp procedure, were 172 +/- 10.4 microU/ml before and 176 +/- 13.5 microU/ml after doxazosin treatment; these levels were significantly higher than the 137 +/- 7.0 microU/ml reading obtained in the normotensive subjects (P < 0.05). Study results show that hypertensive patients tend to be insulin resistant and that treatment with doxazosin improves insulin sensitivity.