Association between antidiabetic drugs and psoriasis risk in diabetic patients: Results from a nationwide nested case-control study in Taiwan

Background: The risk of psoriasis in diabetic patients has rarely been explored. Objectives: We sought to investigate the association between antidiabetic therapies and psoriasis. Methods: The incidence of psoriasis was compared between a representative diabetic cohort and a matched nondiabetic cohort. We next conducted a nationwide cohort study with 1,659,727 diabetic patients using the National Health Insurance Research Database of Taiwan 1997 through 2011. Multivariate conditional logistic regression was used for nested case-control analyses. Results: Incidence rates of psoriasis among diabetic patients and nondiabetic matched control subjects were 70.2 (95% confidence interval [CI] 59.5-80.9) and 42.3 (95% CI 39.5-45.5) per 100,000 person-years, respectively (P < .0001). Frequent insulin use was associated with higher risk of incident psoriasis (adjusted odds ratio 1.29, 95% CI 1.18-1.42) after adjusting for comorbidities, disease duration, and number of hospital visits. Among diabetic patients without history of insulin use, frequent use of thiazolidinedione was associated with lower risk of psoriasis (adjusted odds ratio 0.87, 95% CI 0.77-0.99). Limitations: The National Health Insurance Research Database did not contain information regarding disease severity, diet, body mass index, lifestyle, or family history. Conclusion: Among diabetic patients, regular insulin use is associated with psoriasis development. Frequent use of thiazolidinedione may be associated with modest reduction in psoriasis risk.