Association of dexamethasone use with COVID-19 outcomes in hospitalized patients with diabetes: a propensity score-matched cohort study

Individuals with diabetes mellitus (DM) are known to face a heightened risk of severe complications from COVID-19. Although dexamethasone is widely used as a core treatment for patients with severe forms of the disease, evidence specifically addressing its effectiveness in diabetic populations remains scarce and sometimes inconsistent. This study aimed to evaluate whether dexamethasone administration is associated with in-hospital mortality and intensive care unit (ICU) admission among diabetic patients hospitalized with COVID-19. This retrospective cohort included adult patients with diabetes who were admitted for COVID-19. Participants were categorized as having received dexamethasone during hospitalization. To minimize confounding, propensity score matching (PSM) using nearest-neighbor selection was applied, and covariate balance was assessed using standardized mean differences (SMD). ICU admission was analyzed using logistic regression, while in-hospital mortality was examined through a log-logistic accelerated failure time (AFT) model. Across both unmatched and matched analyses, dexamethasone use showed no statistically significant association with ICU admission. In time-to-death analyses, dexamethasone appeared to prolong survival in the unmatched group; however, this effect was not statistically significant after PSM, suggesting that baseline differences between treatment groups may have driven the initial association. Among diabetic patients hospitalized with COVID-19, dexamethasone use was not significantly associated with in-hospital mortality or ICU admission after PSM. The discrepancy between unmatched and matched findings suggests that confounding factors likely contributed to the apparent survival benefit observed before matching. These results do not imply a lack of therapeutic value for dexamethasone but highlight the importance of cautious interpretation in diabetic populations and underscore the need for future studies with detailed documentation of disease severity, treatment timing, and dosing.