Does carvedilol impair insulin sensitivity in heart failure patients without diabetes?

Background: An increased risk for impaired glucose tolerance or diabetes was shown in patients on beta-blockers, whereas alphal blockers seem to have favorable effects on glycemic profile. In this study, the metabolic effect of carvedilol in nondiabetic patients with chronic heart failure (CHF) was evaluated. Methods and Results: Twenty-eight nondiabetic CHF patients were enrolled. Before being started on carvedilol and on the highest tolerated dose, each patient underwent an oral glucose tolerance test and fasting insulin, glycohemoglobin, lipid concentrations were measured and insulin sensitivity indices (HOMA, ISI-gly, and ISI-composite) were calculated. An impaired glucose tolerance was found (2-hour glycemia 144 +/- 42 mg/dL), with a fasting glycemia at upper limits of normal (108 +/- 13 mg/dL) and no significant differences between basal and carvedilol treatment measurements. Fasting insulinemia significantly decreased during carvedilol treatment (13.6 +/- 7.3 versos 9.8 +/- 5.1 mu U/mL; P = .022), with a reduction of the HOMA index (3.75 +/- 1.95 versus 2.73 +/- 1.47; P = 034) and an increase of the ISI-gly index (0.85 +/- 0.22 versus 1.03 +/- 0.31; P = .025). The lipoprotein profile did not significantly change. Conclusion: Carvedilol might have some positive metabolic effects on increasing insulin sensitivity that would make it suitable for diabetic patients that have a worse prognosis than non diabetic patients with CHF.