Increased risk of diabetes mellitus in relation to the severity of psoriasis, concomitant medication, and comorbidity: a nationwide population-based cohort study.

The association between psoriasis and diabetes mellitus (DM) has been explored previously. However, no studies have been reported regarding the severity of psoriasis, comorbidities, and concomitant medications on the risks of DM in patients with psoriasis. We sought to evaluate the impact of the severity of psoriasis, comorbidities, and concomitant medications on the risk of type 2 DM in patients with psoriasis. We conducted a cohort study with 14,158 adults with psoriasis and adults without psoriasis using data from the Taiwan National Health Insurance Research Database. Cox regression models using time-varying covariates were used. After the comorbidities and concomitant medications were adjusted for, psoriasis was found to be independently associated with an increased risk of DM (severe: hazard ratio, 2.06 [95% confidence interval, 1.58-2.68] vs mild: hazard ratio, 1.28 [95% confidence interval, 1.05-1.55]). Other independent risk factors included age, Cushing disease, and the increased cumulative doses of the thiazide and methotrexate. The National Health Insurance Research Database did not have information regarding the Psoriasis Area and Severity Index, diet, obesity, body mass index, exercise status, and family history of diabetes. Patients with psoriasis have a higher risk of developing DM. The risks vary depending on the severity of psoriasis, comorbidities, and concomitant medications.