The effect of diabetes mellitus on patients undergoing coronary surgery: A risk-adjusted analysis

Background: Surgical case-mix is seriously worsening, and the results of surgical revascularization on high-risk cohorts should be continuously evaluated. This study investigates the influence of diabetes mellitus on the short and midterm outcome in the modern era of coronary surgery. Methods and Results: Patients who underwent first-time coronary artery bypass grafting from April 1996 to October 2003 were classified into diabetic and nondiabetic groups. Data were prospectively collected and retrospectively analyzed. A total of 5259 patients were studied, and of these 877 (17%) were diabetic. Patients with diabetes were more likely to be female, have a higher body mass index, be in an advanced New York Heart Association class and Canadian Cardiovascular Society class, have a history of congestive heart failure, have a poor ejection fraction, renal failure, and more extensive coronary artery disease than the nondiabetic group (P < .001 for all). In-hospital mortality was 2.2% and 1% for diabetic and nondiabetic patients, respectively; however, diabetes was not found to be an independent risk factor for in-hospital mortality (odds ratio = 1.63; 95% confidence interval 0.92-2.88; P = .089). Postoperative complications were comparable in the two groups, with only renal, neurologic, and gastrointestinal complications significantly associated with diabetes (all P <= .05). There was no association between diabetes mellitus and postoperative infective complications. Diabetes remained an independent predictor of 5-year mortality (hazard ratio 1.55; 95% confidence interval 1.22-1.96; P < .001) and of lower 5-year cardiac-related event-free survival. Conclusion: Despite a worsening cohort, diabetic patients could be surgically revascularized with low morbidity and mortality, comparable with control patients. The negative effect of diabetes mellitus on the longer-term mortality and morbidity remains a problem.