Objectives: To examine the acute effects of captopril administration on insulin sensitivity in normotensive type 1 diabetic patients.
Design: An euglycaemic insulin clamp (150 min) was performed in a randomized order twice in each subject: once with the oral administration of captopril (25 mg), once with placebo, both given in the beginning of the insulin infusion.
Setting: The study was performed at the clinical research laboratory of Helsinki University Hospital, Second and Third Departments of Medicine.
Subjects: We studied seven male, normotensive type 1 diabetic patients with normal body weight, duration of diabetes 15 +/- 2 years, HbA1 9.8 +/- 0.7% and daily insulin dose 47 +/- 4 units. In addition, nine matched healthy control subjects were examined.
Results: During placebo administration glucose disposal rate in the diabetic patients was not significantly different from that in the control subjects. Captopril administration reduced blood pressure in both groups, whereas glucose disposal rate did not change significantly in diabetic or control subjects. When diabetic and control subjects were analysed together, captopril decreased glucose disposal by 9% (P < 0.05).
Conclusions: Acute captopril administration does not improve insulin sensitivity in normotensive type 1 diabetic patients or control subjects.