Metformin Reduced Delirium Risk and All-Cause Mortality: Retrospective Observational Study

Abstract:

Introduction: Delirium is a severe medical illness related with aging. Metformin, oral medication for type 2 diabetes (DM), has been reported to improve age-related disorders including dementia and lower mortality. In this study, we investigated the relationship between metformin use history and delirium risk as well as long term mortality using our previous data set.



Method: Data from total 1404 subjects were analyzed retrospectively. The relationship between metformin use and delirium and the relationship between metformin use and 3-year mortality were analyzed.



Results: 242 subjects were categorized as DM without metformin group and 264 subjects were categorized as DM with metformin group. Prevalence of delirium was 36.0% in DM without metformin group, and 29.2% in DM with metformin group, respectively. Logistic regression analysis showed that the history of metformin usage reduced the risk of delirium in patients with DM (OR=0.50, 95% CI; 0.32–0.79, p=0.003) after controlling for age, sex, dementia status, BMI, and insulin use history. 3-year mortality in DM without metformin group was higher than in DM with metformin group (p=0.035, log-rank test corrected by holm method). Cox proportional hazard model showed that metformin use history decreased risk of 3-year mortality after adjustment for age, sex, CCI, BMI, history of insulin usage, and delirium status (HR = 0.69, 95%CI; 0.48–0.98, p = 0.038).



Discussion: Positive benefit of metformin on delirium risk and mortality can provide insights about potential preventive and therapeutic opportunity for delirium commonly seen among aged population.





Key Words: delirium, metformin, diabetes mellitus, mortality, aging