Abstract
Background: Diabetes mellitus is associated with poorer long-term outcomes following coronary artery bypass graft (CABG) surgery. However, little is known about the impact of diabetes mellitus on outcomes during the first 12 months following CABG. Objectives: To examine the relationship between diabetes mellitus and outcomes during the 12 months following CABG. Methods: The Routine versus Selective Exercise Treadmill Testing after Coronary Artery Bypass Grafting (ROSETTA-CABG) Registry is a prospective, multicentre study examining the use of functional testing after CABG surgery. A total of 398 patients who were enrolled in the ROSETTA-CABG Registry were examined. Diabetic status was defined by medication use at discharge. Only patients undergoing a first successful CABG (all ischemic areas thought to be revascularized) were included. Results: Among the 398 patients, 37 (9.3%) were receiving insulin, 67 (16.8%) were receiving oral hypoglycemic agents, and 294 (73.9%) were not receiving insulin or oral hypoglycemic agents. Insulin-treated patients had a higher 12-month incidence of composite clinical events consisting of readmission for unstable angina, myocardial infarction or death than did oral hypoglycemic-treated patients and nondiabetic patients (21.6% versus 4.5% and 6.0%, respectively; P=0.0003). Insulin-treated patients were also more likely to undergo repeat cardiac catheterization than were oral hypoglycemic-treated patients and nondiabetic patients (18.9% versus 8.8% and 7.9%, respectively; P=0.03). After controlling for other variables, use of insulin was independently associated with a composite of adverse clinical events (OR 3.80, 95% CI 1.5 to 9.6, P=0.005). Conclusions: During the 12-month period after a successful CABG, insulin-treated patients had a higher rate of adverse cardiac events than did patients receiving oral hypoglycemic agents and non-diabetic patients. These results suggest that diabetic patients may benefit from more aggressive surveillance during the first year after CABG surgery.