Association of Metformin Use During Hospitalization and Mortality in Critically Ill Adults With Type 2 Diabetes Mellitus and Sepsis*

OBJECTIVES: Whether metformin exposure is associated with improved outcomes in patients with type 2 diabetes mellitus and sepsis. DESIGN: Retrospective cohort study. SETTING: Patients admitted to ICUs in 16 hospitals in Pennsylvania from October 2008 to December 2014. PATIENTS: Adult critical ill patients with type 2 diabetes mellitus and sepsis. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We conducted a retrospective cohort study to compare 90-day mortality in diabetic patients with sepsis with and without exposure to metformin during hospitalization. Data were obtained from the electronic health record of a large healthcare system in Pennsylvania from October 2008 to December 2014, on patients admitted to the ICU at any of the 16 hospitals within the system. The primary outcome was mortality at 90 days. The absolute and adjusted odds ratio (OR) with 95% CI were calculated in a propensity score-matched cohort. Among 14,847 patients with type 2 diabetes mellitus and sepsis, 682 patients (4.6%) were exposed to metformin during hospitalization and 14,165 (95.4%) were not. Within a total of 2,691 patients subjected to propensity score-matching at a 1:4 ratio, exposure to metformin ( n = 599) was associated with decreased 90-day mortality (71/599, 11.9% vs 475/2,092, 22.7%; OR, 0.46; 95% CI, 0.35–0.60), reduced severe acute kidney injury (50% vs 57%; OR, 0.75; 95% CI, 0.62–0.90), less Major Adverse Kidney Events at 1 year (OR, 0.27; 95% CI, 0.22–0.68), and increased renal recovery (95% vs 86%; OR, 6.43; 95% CI, 3.42–12.1). CONCLUSIONS: Metformin exposure during hospitalization is associated with a decrease in 90-day mortality in patients with type 2 diabetes mellitus and sepsis.