Contemporary Outcomes of Coronary Artery Bypass Grafting Among Patients With Insulin-Treated and Non-Insulin-Treated Diabetes

Background: More than 40% of patients undergoing coronary artery bypass grafting (CABG) have diabetes. However, it is unknown how insulin treatment status influences cardiac surgical outcomes among patients with diabetes. Methods: All isolated CABG, CABG plus aortic valve replacement or plus mitral valve repair/replacement procedures performed in 2012 were extracted from the California CABG Outcomes Reporting Program database. Patients were grouped into three categories: (1) no diabetes, (2) non-insulin-treated diabetes (NITDM), and (3) insulin-treated diabetes (ITDM). Demographic and clinical baseline characteristics and observed postoperative major adverse events, including 30-day mortality, stroke, deep sternal wound infection, prolonged ventilation, new dialysis requirement, renal failure, and 30-day readmission were compared. Multivariable logistic regression models were developed for predicting the impact of NITDM and ITDM on postoperative major adverse events. Results: A total of 14,051 patients underwent isolated CABG or CABG plus aortic/mitral valve procedures in California during 2012; 6700 (47.7%) had no diabetes, 5165 (36.8%) had NITDM, and 2183 (15.6%) had ITDM. Compared with the nondiabetic and NITDM groups, the ITDM group was younger, more frequently women and nonwhite, and had a higher prevalence of preoperative comorbidities (all p < 0.05). After adjusting for baseline risk factors and surgery type compared with patients without diabetes, both NITDM and ITDM were associated with significantly increased risk of major adverse events [NITDM: adjusted odds ratio (AOR), 1.15, 95 % confidence interval (CI), 1.04 to 1.26, p= 0.005; ITDM: AOR, 1.49, 95% CI, 1.32 to 1.68, p < 0.0001]. A subgroup comparison indicated a similar gradient of risk for each category of cardiac surgery. Conclusions: Patients with diabetes undergoing CABG have substantially increased risk of major adverse events. Patients with ITDM represent an especially high-risk group.