Preoperative diabetes duration and long-term outcomes in patients with acute myocardial infarction undergoing coronary artery bypass grafting

Background: The association between preoperative diabetes mellitus (DM) duration and outcomes of coronary artery bypass grafting (CABG) remains unclear. This study aimed to investigate the relationship between DM duration at the time of CABG and long-term outcomes, particularly in patients with acute myocardial infarction. Methods: Using data from South Korea's National Health Insurance Service database, the study included adult patients who underwent first-time isolated CABG with an acute myocardial infarction diagnosis between 2005 and 2021. Patients with DM were categorized based on whether their diagnosis occurred within 5 years before CABG. Patients with impaired fasting glucose were also classified. The primary outcome was all-cause overall mortality. The secondary outcome was repeat revascularization. Results: A total of 21,957 patients (median age, 65.0 years) were categorized into 4 groups: without DM, impaired fasting glucose, DM diagnosed within 5 years, and DM diagnosed more than 5 years before CABG. Patients with DM <5 years had a higher overall mortality rate (hazard ratio, 1.16; 95% CI, 1.08-1.24), and those with DM >5 years had an even higher rate (hazard ratio, 1.36; 95% CI, 1.27-1.46) compared with those without DM. The incidence rate of repeat revascularization was significantly higher in those with DM >5 years (hazard ratio, 2.07; 95% CI, 1.89-2.28). Conclusions: The duration of DM before CABG is correlated with worse clinical outcomes. A prolonged period of DM before CABG may be a significant risk factor for poorer long-term outcomes in patients with acute myocardial infarction.