Association of long-term environmental exposures in pregnancy and early life with islet autoimmunity development in children in Bavaria, Germany

Objective: Incidence of early-onset type 1 diabetes (T1D) has been increasing worldwide. Only few studies examined the relationship between geographical environmental variation and T1D incidence or its presymptomatic stage of islet autoimmunity. Our study aimed to investigate the effect of long-term environmental exposures during pregnancy and early life on childhood islet autoimmunity. Research Design and Methods: We used data from the Fr1da cohort study which screened children aged 1.75-5.99 years for multiple islet autoantibodies in Bavaria, Germany between 2015 and 2019. We included 85,251 children with valid residential information. Daily averages for particulate matter with a diameter < 2.5 mu m, nitrogen dioxide, ozone, air temperature, and greenness were averaged for each zip-code or directly assigned to the addresses. The exposure windows included pregnancy, the first year and the first two years of life. Generalized additive models adjusting for individual and socioeconomic variables were used to investigate associations between environmental exposures and islet autoimmunity development. Results: Islet autoimmunity was diagnosed in 272 children. Colder air temperature during pregnancy was associated with developing islet autoimmunity at the address (per 2.2 ?C decrease, Odds ratio (OR): 1.49; 95% Confidence interval (CI): 1.21-1.83) and zip-code level (per 2.4 ?C decrease, OR: 1.31; 95% CI: 1.08-1.59). Using the addresses, significant associations were also observed during the first years of life. Conclusion: In this study, children's residential exposure to lower levels of air temperature during pregnancy and early life increased the risk of islet autoimmunity before the age of six.