The effect of diabetes on long-term outcomes in patients following coronary artery bypass grafting

Objectives: Diabetes mellitus is a risk factor for coronary artery disease, but its role following CABG is still unclear and few data on long-term outcomes are available. This study aimed to evaluate the impact of diabetes on long-term outcomes after CABG. Methods: The PRIORITY project is an observational cohort study merging two prospective multicentre studies on isolated CABG. Follow-up information was obtained through administrative databases and was truncated 10 years after the intervention. Baseline differences between patients with and without diabetes were balanced with inverse probability of treatment weighting. Results: The cohort consisted of 10,989 patients with complete follow-up information who underwent isolated CABG (diabetes 32.3%). Diabetes did not affect short-term mortality (OR 0.90, 95% CI 0.73-1.10) and repeat revascularization (OR 0.79, 95% CI 0.42-1.49), while it is related to lower incidence of 30-day MACCE (OR 0.67, 95% CI 0.60-0.76), AMI (OR 0.60, 95% CI 0.51-0.70) and stroke (OR 0.47, 95% CI 0.28-0.77). Diabetic patients had a higher long-term risk for MACCE (weighted HR 1.31, 95% CI 1.26-1.37), mortality (HR 1.45, 95% CI 1.37-1.53), as well as stroke (HR 1.38, 95% IC 1.25-1.53) and myocardial infarction (HR 1.39, 95% CI 1.26-1. 53). Diabetes had not been associated with an increased incidence of repeated revascularization up to 10 years (HR 1.04, 95%IC 0.96-1.12). Conclusions: Diabetic patients had worse long-term outcomes. Diabetes may have a greater negative impact on micro-vasculopathy than grafts, as evidenced by the increased long-term incidence of myocardial infarction without affecting myocardial revascularization.