Abstract 4357554: Association between metformin exposure and outcomes in diabetic patients undergoing cardiac surgery: A retrospective cohort study

Background: This study aimed to evaluate the association between metformin exposure and in-hospital outcomes in critically ill patients with type 2 diabetes mellitus (T2DM) who underwent cardiac surgery. Methods: T2DM patients undergoing cardiovascular surgery were included from the Medical Information Mart for Intensive Care IV database. The primary endpoints were 30-day all-cause mortality, while the secondary endpoints included 90-day and 360-day mortality. Multivariable Cox regression analysis was used to evaluate the correlation between metformin exposure and mortality. Subgroup analysis and sensitivity analysis (including propensity score analysis) were used to test the stability of the conclusion. Results: A total of 2694 T2DM patients undergoing cardiovascular surgery were included (1127 in the metformin group and the rest 1567 in the non-metformin group). Compared with the non-metformin group, patients in the metformin group had a significantly lower 30-day mortality (0.4% vs. 4.5%, p<0.001). After adjustment for potential confounders, multivariable Cox regressions indicated that metformin exposure was associated with reduced incidences of 30-day [HR (95%CI): 0.19 (0.07-0.54), p=0.002], 90-day [HR (95%CI): 0.24 (0.12-0.47), p<0.001] and 360-day death [HR (95%CI): 0.35 (0.23-0.52), p<0.001]. Subgroup analysis, sensitivity analysis, and propensity score matching analysis indicated consistent relationships between metformin exposure and the primary endpoints. Conclusion: Metformin exposure was related to reduced short-term, mid-term, and long-term mortality in T2DM patients undergoing cardiovascular surgery. Further randomized controlled trials are required to clarify this association.