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

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.

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 < or = .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.

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.