Risk of Cardiovascular Events in Patients With Diabetes Mellitus on β-Blockers

Although the use of beta-blockers may help in achieving maximum effects of intensive glycemic control because of a decrease in the adverse effects after severe hypoglycemia, they pose a potential risk for the occurrence of severe hypoglycemia. This study aimed to evaluate whether the use of beta-blockers is effective in patients with diabetes mellitus and whether its use is associated with the occurrence of severe hypoglycemia. Using the ACCORD trial (Action to Control Cardiovascular Risk in Diabetes) data, we performed Cox proportional hazards analyses with a propensity score adjustment. The primary outcome was the first occurrence of a cardiovascular event during the study period, which included nonfatal myocardial infarction, unstable angina, nonfatal stroke, and cardiovascular death. The mean follow-up periods (+/- SD) were 4.6 +/- 1.6 years in patients on beta-blockers (n=2527) and 4.7 +/- 1.6 years in those not on beta-blockers (n=2527). The cardiovascular event rate was significantly higher in patients on beta-blockers than in those not on beta-blockers (hazard ratio, 1.46; 95% confidence interval, 1.24-1.72; P<0.001). In patients with coronary heart disease or heart failure, the cumulative event rate for cardiovascular events was also significantly higher in those on beta-blockers than in those not on beta-blockers (hazard ratio, 1.27; 95% confidence interval, 1.02-1.60; P=0.03). The incidence of severe hypoglycemia was significantly higher in patients on beta-blockers than in those not on beta-blockers (hazard ratio, 1.30; 95% confidence interval, 1.03-1.64; P=0.02). In conclusion, the use of beta-blockers in patients with diabetes mellitus was associated with an increased risk for cardiovascular events.