Comparison of carvedilol and metoprolol on serum lipid concentration in diabetic hypertensive patients

CONTEXT: Vasoconstricting beta-blocker use is associated with a reduction in HDL cholesterol, higher triglyceride, total cholesterol and LDL cholesterol levels, whereas carvedilol, a vasodilating beta-blocker, has not been associated with these effects. OBJECTIVE: To compare in a randomized, double-blind study, the effects of the beta 1-blocker metoprolol tartrate with the combined alpha 1, beta-blocker carvedilol on serum lipid concentrations. METHODS: A prospective randomized, double-blind, parallel-group trial compared the effects of carvedilol and metoprolol on total cholesterol, triglycerides, calculated LDL, HDL and non-HDL cholesterol levels at baseline and after 5 months of therapy as a secondary objective in the Glycemic Effects in Diabetes Mellitus: Carvedilol-Metoprolol Comparison in Hypertensive (GEMINI) study. In this study, 1235 participants with type 2 diabetes and hypertension who were receiving renin-angiotensin system blockers were randomized either to carvedilol, receiving 6.25-25 mg twice daily, or to metoprolol tartrate, receiving 50-200 mg twice daily. If needed, hydrochlorothiazide and a dihydropyridine calcium channel blocker were added to achieve blood pressure goals. RESULTS: In the metoprolol tartrate group, triglycerides and non-HDL cholesterol increased and both the LDL and the HDL cholesterol levels decreased. In the carvedilol group, total LDL and HDL cholesterol decreased, non-HDL cholesterol was unchanged and triglycerides increased. Comparing the carvedilol and metoprolol tartrate groups, there was no statistically significant difference in LDL and HDL cholesterol levels, but there was a significantly greater decreases with carvedilol in total cholesterol -2.9%, 95% confidence interval (CI) -4.60 to -1.15, p < 0.001, triglycerides (-9.8%, 95% CI -13.7, -5.75%, p < 0.001) and non-HDL cholesterol (-4.03%, 95% CI -6.3 to -1.8, p < 0.0006). At the end of the study, significantly more participants in the metoprolol tartrate group had had initiation of statin therapy or the statin dose increased than those in the carvedilol group (11 vs. 32%, p = 0.04). CONCLUSIONS: In patients with type 2 diabetes currently receiving a renin-angiotensin blocker, compared with metoprolol tartrate, the addition of carvedilol for blood pressure control resulted in a significant decrease in triglyceride, total cholesterol and non-HDL cholesterol levels. The use of metoprolol resulted in a significantly greater rate of initiation of statin therapy or an increase in the dose of existing statin therapy when compared with carvedilol utilization.