Comparing the Clinical Outcomes Between Insulin-treated and Non-insulin-treated Patients With Type 2 Diabetes Mellitus After Coronary Artery Bypass Surgery

Several studies have shown coronary artery bypass surgery (CABG) to be beneficial in patients with type 2 diabetes mellitus (T2DM) and multivessel coronary artery diseases. Patients with insulin-treated T2DM (ITDM) are usually patients with poor glycemic control and are expected to suffer more complications compared with patients with non-insulin-treated T2DM (NITDM). However, the adverse clinical outcomes in patients with ITDM and NITDM after CABG are still not very clear. Hence, to solve this issue, we aim to compare the short-and long-term adverse clinical outcomes in a larger number of patients with ITDM and NITDM after CABG, respectively.Randomized controlled trials and observational studies comparing the adverse clinical outcomes such as mortality, major adverse events (MAEs), stroke, myocardial infarction, and repeated revascularization in patients with ITDM and NITDM after CABG have been searched from Medline, EMBASE, Cochrane, and PubMed databases. A short-term follow-up (≤30 days) and a long-term follow-up (≥1 year) were considered. Odds ratio (OR) with 95% confidence interval (CI) was used to express the pooled effect on discontinuous variables and the pooled analyses were performed with RevMan 5.3.Eleven studies involving a total of 64,152 patients with T2DM (23,781 patients with ITDM and 40,371 patients with NITDM) have been included in this meta-analysis. During the short-term follow-up period, patients with ITDM had a significantly higher mortality (OR: 1.47; 95% CI: 1.33-1.61, P < 0.00001) and MAEs (OR: 1.66; 95% CI: 1.48-1.87, P < 0.00001). During the long-term follow-up period, patients with ITDM still had a significantly higher rate of mortality, MAEs, and stroke (OR: 1.23, 95% CI: 1.02-1.49, P = 0.03; OR: 1.50, 95% CI: 1.07-2.12, P = 0.02; OR: 1.39, 95% CI: 1.22-1.59, P < 0.00001, respectively) after CABG. However, our results showed similar repeated revascularization rate between the ITDM and NITDM groups after CABG (OR: 1.31, 95% CI: 0.81-2.12, P = 0.27).According to this study, patients with ITDM had a significantly higher rate of mortality and MAEs compared with patients with NITDM after CABG. Stroke was also significantly higher in patients with ITDM during a long-term follow-up period. However, since the result for the long-term mortality had a higher heterogeneity as compared with the other subgroups, and because a similar revascularization rate was observed between the ITDM and NITDM groups after CABG maybe because of a limited number of patients analyzed, further studies still need to be conducted to completely solve this issue.