Influence of nebivolol and enalapril on metabolic parameters and arterial stiffness in hypertensive type 2 diabetic patients

Objective To compare the effects of a cardioselective betablocker (nebivolol) with those of an angiotensin-converting enzyme inhibitor (enalapril) on parameters of insulin sensitivity, peripheral blood flow and arterial stiffness during one extended glucose clamp experiment. Design A randomized, double-blind, crossover trial, consisting of two 12-week treatment phases separated by a 4-week wash-out phase. Methods Patients with type 2 diabetes and arterial hypertension were randomly assigned to one of two treatment sequences (nebivolol-enalapril, enalapril nebivolol). Haemodynamic, metabolic and other laboratory measurements were carried out on the first and last day of each treatment period by means of a glucose clamp experiment that also involved the measurement of blood flow and arterial stiffness. Results Twelve patients were included in this study, of which two dropped out early. Efficacy parameters were therefore available for 10 patients. There was no significant difference in any of the primary efficacy parameters. Moreover, the effects on blood pressure did not significantly differ between both treatments. Six adverse events happened during treatment with nebivolol compared with two during treatment with enalapril, but only one was regarded as possibly related to the treatment. Conclusions This pilot study shows that the combined measurement of insulin sensitivity, blood flow and arterial stiffness is feasible. Nebivolol and enalapril did not show different effects with regard to these parameters in hypertensive diabetic patients. If these results are confirmed in larger clinical trials, this would argue against the reservations against beta-blockers as drugs of first choice in patients with diabetes because of potential metabolic side-effects. J Hypertens 24:1397-1403 (c) 2006 Lippincott Williams & Wilkins.