Initial Diabetes Therapy After Coronary Artery Bypass Grafting and Long‐Term Outcomes

BACKGROUND: Type 2 diabetes (T2D) is common among patients undergoing coronary artery bypass grafting (CABG), but optimal post-CABG glucose-lowering therapy remains uncertain. METHODS: We conducted a retrospective cohort study using the OptumLabs Data Warehouse of adults with T2D undergoing isolated CABG from 2012-2024. Follow-up began 30 days after discharge. Glucose-lowering therapy was modeled as a time-varying exposure with patients contributing no-observed-therapy person-time until the first qualifying post-discharge fill. Pairwise comparisons used stabilized inverse probability of treatment weighting. The primary outcome was all-cause mortality; secondary outcomes were heart failure hospitalization, stroke, and repeat coronary revascularization. RESULTS: Among 19,237 patients, 24.9% had no observed post-discharge therapy, 42.8% received metformin, 22.9% received insulin, and 9.4% received GLP-1RA/SGLT2i therapy. All active therapies were associated with lower mortality compared with no observed therapy, including GLP-1RA/SGLT2i (HR 0.71, 95% CI 0.58-0.87), metformin (HR 0.60, 95% CI 0.55-0.66), and insulin (HR 0.75, 95% CI 0.67-0.84). Among active therapies, metformin was associated with lower mortality than insulin (HR, 0.61 [0.54-0.70]); GLP-1RA/SGLT2i comparisons with metformin and insulin were less precise. Metformin was also associated with lower cumulative incidence of heart failure hospitalization than no observed therapy and insulin, and lower stroke incidence than insulin. CONCLUSIONS: Observed glucose-lowering therapy initiation after CABG was associated with lower mortality compared with no observed therapy across all active treatment groups. These findings highlight a potential care gap and suggest that proper initiation of diabetes therapy after CABG represents an important opportunity to improve long-term outcomes following surgical revascularization.