Insulin sensitivity in hypertensive Type 2 diabetic patients after 1 and 19 days' treatment with trandolapril

The aims of this study were to examine the effects of trandolapril, a long acting angiotensin converting enzyme (ACE) inhibitor with high tissue uptake, on insulin sensitivity and lipid concentrations in hypertensive patients with Type 2 diabetes mellitus.

Insulin sensitivity was assessed after an acute dose (day 3) and 19 days continuous treatment (days 3-21) using the isoglycaemic, hyperinsulinaemic glucose clamp with D[3-3H] labelled glucose, a variable D[3-3H] priming dose and a 'hot' glucose infusion. Rates of glucose appearance (Ra) and glucose disappearance (Rd) were isotopically determined during the basal and insulin stimulated periods of the clamp. Twenty-four (5 female) hypertensive (blood pressure >75th centile for age and sex) patients with Type 2 diabetes mellitus were studied. Patients were randomized, in a double-blind manner, to either trandolapril 4 mg daily (T) or placebo (P).

Baseline (day 1) systolic (mean +/- SD; P 164+/-14 and T 168+/-13 mm Hg) and diastolic (P 93+/-6, and T 98+/-10 mm Hg) blood pressures were comparable. On days 3 and 21, significant reductions were observed in both groups (P<0.001). In the trandolapril-treated group, serum trandolapril concentrations were >200 pg/ml on days 3 and 21, in all patients apart from one subject at a single visit, while trandolapril was undetectable in the placebo group. Body mass index (BMI) was greater in T compared with P (32.2+/-5.4 v. 28.3+/-4.6, P = 0.07). After correcting for BMI, basal hepatic glucose output (HGO) P 2.6 (95% CI 2.23-3.13) and T 1.91 (1.33-2.51) mg x kg(-1) x min(-1) and clamped HGO P 0.32 (-0.44-1.09) and T 0.87 (0.40-1.34) mg x kg(-1) x min(-1) were similar in both groups. The insulin sensitivity index was comparable in both groups on all days. Total cholesterol concentrations were similar in both groups throughout the study. Triglyceride concentrations were significantly lower in group P 1.38 (1.07-1.68); T 2.14 (1.70-2.58) mmol/l, P<0.01), no significant treatment effect being observed.

An acute dose and 19 days' continuous treatment with trandolapril resulted in no change in insulin sensitivity or plasma lipid profiles in patients with Type 2 diabetes mellitus and hypertension. These data support the metabolic neutrality of trandolapril in patients with Type 2 diabetes mellitus and hypertension.