The bidirectional association between type 2 diabetes and psoriasis: Two retrospective cohort studies.

ABSTRACT

BACKGROUND: Inflammation plays a crucial role in both type 2 diabetes mellitus (T2DM) and psoriasis pathogenesis; thus, a bidirectional association between them is likely suspected. AIMS: We investigated the possible bidirectional association between T2DM and psoriasis. METHODS: Using the Taiwan National Health Insurance Research Database, we conducted two retrospective cohort studies. The analysis of psoriasis onset in relation to T2DM status included 31,697 patients with diabetes and 126,788 nondiabetic control subjects (Analysis 1). The analysis of T2DM onset in relation to psoriasis status included 1,947 psoriatic patients and 7,788 nonpsoriatic control subjects (Analysis 2). The follow-up period was from 2000 to the date of the outcome of interest, date of death, or December 31, 2013. Cox proportional models were used to estimate the relative hazards. RESULTS: In Analysis 1, Kaplan-Meier (KM)-based cumulative incidence of psoriasis was higher in the T2DM cohort than that in the non-T2DM cohort (1.2% vs. 0.7%). The covariate-adjusted hazard ratio (HR) was 1.40 [95% confidence interval (CI), 1.20-1.63] for patients with T2DM. Analysis 2 revealed KM-based cumulative T2DM incidences of 18.7% and 13.1% in psoriatic and nonpsoriatic subjects, respectively. The adjusted HR for incident T2DM was higher in patients with psoriasis (1.38; 95% CI, 1.20-1.58). LIMITATION: This article may not represent the population worldwide and patient selection bias may exist. CONCLUSION: Our results provide evidence for a bidirectional T2DM-psoriasis association. T2DM and psoriasis are common worldwide; thus, our findings have public health implications for the early identification and management of these comorbid diseases.