There is limited information about the association between diabetes, its treatment, and long-term angiographic and clinical outcomes in patients undergoing coronary artery bypass graft surgery (CABG). We evaluated the association of diabetes and its treatment with 1-year angiographic graft failure and 5-year clinical outcomes in patients undergoing CABG.

Using data from 3,014 patients in PREVENT IV, we analyzed angiographic and clinical outcomes in patients with and without diabetes and among those who did and did not receive insulin before CABG. Logistic regression and Cox proportional hazards models were used to adjust for differences in baseline variables.

Overall, 1,139 (37.8%) patients had diabetes. Of these, 305 (26.8%) received insulin. One-year rates of vein graft failure were similar in patients with and without diabetes but, among diabetics, tended to be higher in patients who received insulin compared with those who did not. At 5 years, rates of death, myocardial infarction, or revascularization were higher among patients with compared with those without diabetes (adjusted hazard ratio 1.57; 95% CI 1.26-1.96; P < .001) and, among diabetics, higher among those who received insulin (adjusted hazard ratio 1.15; 95% CI 1.02-1.30; P = .02).

Patients with diabetes had similar rates of vein graft failure but worse clinical outcomes than patients without diabetes. Patients who received insulin had significantly worse clinical outcomes than patients who did not receive insulin. Further studies to better understand the mechanism behind these findings and to improve the outcomes of patients with insulin-requiring diabetes undergoing CABG surgery are warranted.