Metformin's impact on delirium in diabetic cardio surgery patients

The effect of metformin on postoperative delirium (POD) in patients with type 2 diabetes mellitus (T2DM) undergoing cardiovascular surgery remains unclear. This study aimed to evaluate whether metformin use reduces POD risk in this high-risk population by analyzing data from Taiwan's National Health Insurance Research Database using propensity score matching (PSM).

We included T2DM patients who underwent coronary artery bypass grafting (CABG) or valve replacement between 2015 and 2018. PSM was used to balance covariates between metformin users and non-users. Logistic regression and Kaplan-Meier analyses were performed to assess POD risk and its cumulative incidence.

Metformin use was associated with a significantly reduced risk of POD (adjusted odds ratio [aOR], 0.52; 95% confidence interval [CI], 0.40-0.67). A dose-response trend was observed, with decreasing aORs for higher cumulative metformin exposure. Protective factors included higher income, urban residency, and statin use; risk factors included older age, prolonged anesthesia, higher aDCSI, CCI scores, and depression.

Metformin significantly lowers the risk of POD in T2DM patients undergoing cardiovascular surgery, showing a clear dose-dependent protective effect. These findings highlight metformin's potential as a chemopreventive agent against post-surgical complications in this population.