Background: The aim of this study was to assess the long-term risk of death or acute myocardial infarction (AMI) in patients with diabetes mellitus (DM) compared with that in patients without DM after coronary artery bypass grafting (CABG).
Methods: National registers were used to record death or AMI occurring in 6727 patients who had CABG during 1980 to 1995. Diabetes mellitus in 856 patients (13%) was classified as type 1 (6%) or type 2 treated with insulin (29%), oral drugs (46%), or diet (19%).
Results: The risk of death < or = 30 days of the operation was increased in patients with insulin-treated type 2 DM (odds ratio [OR] 4.6, 95% CI 2.5-8.4) and in those on oral antidiabetic drugs (OR 2.0, 95% CI 1.0-3.8), but not in diet-treated diabetic patients, compared with that in patients without diabetes. At 10 years, the relative risk of death or having an AMI was 1.8 (95% CI 1.5-2.2) in insulin-treated patients and 1.4 (95% CI 1.2-1.7) in patients on oral drugs. No increased risk of late death or AMI was observed in diet-treated patients with diabetes compared with patients without diabetes. Survival at 10 years without an AMI was 40% in insulin-treated type 2 diabetic patients, 48% if on oral drugs, and 59% if diet managed, compared with 66% in nondiabetic patients.
Conclusion: Type 2 DM requiring insulin treatment or oral antidiabetic drugs is associated with an increased early and long-term risk of death or AMI after CABG, whereas diet-treated patients have a risk similar to that in patients without diabetes.