[Glucose tolerance test and insulin secretion in patients with essential hypertension. Effect of enalapril].

PURPOSE: To investigate the effects of enalapril upon glucose and insulin metabolism in patients with essential hypertension. METHODS: After 4 weeks of washout and 2 weeks of placebo therapy, 10 hypertensive patients were treated with enalapril for 12-14 weeks. Intravenous glucose tolerance test (IVGTT) during 182 minutes was performed before and after treatment. Venous blood samples were drawn for glucose and insulin determinations. RESULTS: Enalapril caused a significant fall on systolic (-19 +/- 3 mmHg) and diastolic (-10 +/- 2 mmHg) blood pressure. During IVGTT, enalapril induced a small decrease in the area under the curve of glucose (placebo 18,966 +/- 732.6 mg/dl.min and enalapril 17,575 +/- 916.1 mg/dl.min) associated with a small increase in the area under the curve of insulin (placebo 3,155 +/- 446.99 mU/ml.min and enalapril 3.577 +/- 393.92 mU/ml.min). A small rise in the disappearance rate of glucose (Kg) was also observed following enalapril (placebo 2.09 +/- 0.33 and enalapril 2.56 +/- 0.53). The insulin responsiveness to glucose increased significantly from 0.16 +/- 0.020 during placebo to 0.21 +/- 0.023 during enalapril. The insulin sensitivity remained unchanged (placebo 1.97 +/- 0.24 and enalapril 1.83 +/- 0.21). CONCLUSION: In hypertensive patients, the treatment with enalapril induced a small increase (not significant) in glucose tolerance caused by a significant rise in insulin responsiveness to glucose since no modification in insulin sensitivity was observed.