Abstract

The effects of enalapril treatment on blood glucose, insulin, and C-peptide levels and effects on the reninangiotensin aldosterone system were studied in 22 hypertensive patients with non-insulin-dependent diabetes. After a 4-wk run-in period during which all previous antihypertensive drugs were discontinued, treatment was commenced with one daily dose of 10 mg enalapril. The dose was adjusted upward at 3-wk intervals to a maximum of 40 mg daily. In 3 subjects, addition of a thiazide diuretic was required after 9 wk of treatment. At completion of run-in and after 9 and 13 wk of treatment, subjects had blood samples drawn after fasting and 2 h after a standardized 1.6-mJ mixed meal. Mean fasting blood glucose at the end of the run-in period was 8.3 ± 0.5 mM and at study completion was 7.3 ± 0.4 mM. Mean postprandial blood glucose was 10.8 ±1.0 mM before treatment and 9.8 ± 0.7 mM at study completion. The changes in fasting and postprandial blood glucose levels were not significant (P = .06 and P = .15, respectively). There was no significant change in glycosylated hemoglobin levels. Fasting and meal-stimulated insulin and C-peptide levels were not altered by enalapril treatment. Treatment was associated with a sustained reduction in plasma angiotensin-converting enzyme activity, an increase in plasma renin activity, reduced plasma aldosterone levels, and significant reductions in supine, seated, and standing arterial blood pressures. There was a small rise in mean plasma potassium from 4.0 ± 0.09 to 4.2 ± 0.09 mM after 3 wk of treatment, but after 9 wk, potassium levels had returned to pretreatment levels. Plasma creatinine levels did not change.