Risk of Type 1 Diabetes Mellitus in Patients with Atopic Dermatitis: A Nationwide Population-Based Cohort Study

<b><i>Introduction:</i></b> Atopic dermatitis (AD) is a disease frequently occurring in children. The immune response is characterized by T-helper (Th)-2-dependent inflammation. Type 1 diabetes mellitus (T1DM) is an autoimmune disease that destroys pancreatic islet beta cells. In contrast, it is mainly mediated by a Th-1-dependent response. An inverted association has been hypothesized between T1DM and AD since Th1 and Th2 responses are mutually inhibitory. <b><i>Methods:</i></b> Data was retrieved from a nationwide healthcare database in Taiwan. A logistic regression model was used to evaluate the association of T1DM in patients with AD within a year. A Cox proportional hazards analysis was used to evaluate the subsequent risk of developing T1DM 1 year after AD diagnosis. <b><i>Results:</i></b> We identified 396,461 patients with AD and 1,585,844 age- and sex-matched controls. During the first year of follow-up, after adjusting variates, the association between T1DM and AD showed no statistical differences (odds ratio: 1.40; 95% confidence interval [CI]: 0.83–2.38, <i>p</i> = 0.207). After excluding those T1DM cases within 1 year of AD diagnosis and those with a follow-up duration of less than 1 year, AD did not significantly increase the risk of T1DM (hazard ratio [HR]: 1.02; 95% CI, 0.83–1.25, <i>p</i> = 0.843). <b><i>Conclusions:</i></b> Our study revealed that there was no significant association between AD and T1DM in the first year after AD diagnosis, and there was no increased risk of T1DM in AD patients in the average 5-year follow-up in our study.