Topical corticosteroid use and risk of type 2 diabetes mellitus: a nationwide cohort study

BACKGROUND: Topical corticosteroids (TCS) are widely used anti-inflammatory treatments for various dermatologic conditions. Although generally considered safe, concerns remain regarding systemic absorption and potentially increase the risk of type 2 diabetes mellitus (T2DM). OBJECTIVE: To investigate the association between TCS exposure-considering potency, cumulative duration, and prescription frequency-and the prospective risk of developing T2DM. METHODS: We conducted a population-based longitudinal cohort study using the National Health Insurance Service database of South Korea. A total of 685 389 adults aged ≥20 years without diabetes at baseline were included. TCS exposure was assessed over a 5-year period based on any TCS use and further characterized by potency, cumulative duration, and prescription frequency, followed by a 6-year outcome ascertainment period. Incident T2DM was defined as the presence of an ICD-10 code (E11-E14) accompanied by at least one prescription for antidiabetic medication. RESULTS: Overall TCS use during a 5-year exposure period was not associated with an increased risk of T2DM after adjusting for potential confounders. However, potent TCS use (adjusted hazard ratio [aHR], 1.15; 95% confidence interval [CI], 1.04-1.26), higher prescription frequency (≥10 prescriptions) (aHR, 1.26; 95% CI, 1.12-1.42), and longer cumulative duration of exposure (≥6 months) (aHR, 1.45; 95% CI, 1.25-1.67) were associated with a higher risk of developing T2DM. In contrast, low-potency TCS use, exposure duration <6 months, and <10 TCS prescriptions were associated with a lower risk of T2DM (aHR, 0.83; 95% CI, 0.75-0.91, aHR, 0.95; 95% CI, 0.90-0.99, and aHR, 0.94; 95% CI, 0.90-0.99, respectively). CONCLUSIONS: In this large nationwide cohort, overall TCS use was not associated with incident T2DM. However, the use of high-potency formulations, longer cumulative duration, and frequent prescriptions were associated with an increased risk of T2DM. These findings underscore the importance of prudent prescribing and targeted metabolic monitoring in patients requiring potent or long-term TCS therapy.