Effects of newly begun carvedilol and nebivolol treatment on insulin resistance and lipid profile in patients with essential hypertension

Beta blockers are one of the major class of drugs for the treatment of hypertension. However they are not recommended as first-line antihypertensive agents in most of the recent guidelines. This negative opinion stems from the side effects of traditional beta blockers on hemodynamic and metabolic parameters. It is known that the new generation beta blockers with vasodilatation capabilities have favorable effects especially on metabolic parameters, and they seem to be superior to the traditional beta blockers. In this study, we aimed to compare the effects of two beta blockers with vasodilator activity, carvedilol and nebivolol, on insulin resistance and lipid profiles in patients with essential hypertension. This study is a prospective, randomized, open-label, clinical trial. The study included 107 patients having essential hypertension, no overt diabetes mellitus, who presented to the cardiology outpatient clinic. All patients were recommended lifestyle changes. Patients were randomized into two groups; 25 mg of carvedilol (o.d.) and 5 mg of nebivolol (o.d.); and doses were started by titration. Fasting plasma glucose, insulin and lipid profile [high density lipoprotein (HDL), low density lipoprotein (LDL), total colesterol, triglyceride, apolipoprotein A-I, apolipoprotein B] were compared in both groups and insulin resistance was calculated by HOMA index (fasting glucose x fasting insulin / 405) before treatment and 4 months after initiation of therapy. During follow-up, 27 patients were excluded and data analysis was performed in 80 patients (carvedilol group n= 40, nebivolol group n= 40). Both carvedilol and nebivolol significantly (p<0.001, p<0.001) and similarly (p=NS) lowered blood pressure and pulse rate. Both drugs had similar (p=NS) and significant favorable effects on glucose (p<0.001), insulin (p<0.01), HOMA-IR (p<0.01), HDL (p<0.001), LDL (p<0.001), total cholesterol (p<0.001) and apolipoprotein B (p<0.05) levels. Neither group showed a significant change (p=NS) in triglyceride and apolipoprotein A-I levels. Body mass index (p<0.05) and waist circumference measurements (p<0.001) were decreased similarly (p=NS) in both groups. In this study we observed that; in patients with newly diagnosed hypertension, new generation beta-blockers, carvedilol and nebivolol, effectively decrease blood pressure; provide beneficial and comparable effects on glucose, insulin, insulin resistance and lipid profile. These data suggest that new generation beta blockers, carvedilol and nebivolol, are suitable for use in the treatment of essential hypertension without causing metabolic adverse effects. These findings should be investigated with comparison of different drug groups in large randomised placebo-controlled studies. Key words: hypertension, insulin resistance, dyslipidemia, carvedilol, nebivolol, beta blocker