Effects of Artificial Light at Night on Body Mass Index and Islet Autoimmunity Development in Children in Bavaria, Germany

Abstract

Background and Aim: Worldwide, incidence of childhood obesity and early-onset type 1 diabetes (T1D) has risen over the past decades. Epidemiological studies have shown that in addition to genetic predisposition, environmental factors such as air pollution and temperature are associated with body mass index (BMI), T1D and its presymptomatic stage of autoimmunity to pancreatic islet cells. This study aimed to investigate the effect of exposure to light at night (LAN) on standardized BMI and islet autoimmunity (having 2 or more islet autoantibodies) in children in Bavaria, Germany. Methods: Exposure to LAN at baseline was assigned to the residential addresses of 52,636 children (<6 years of age) participating in the Fr1da study from 2015 to 2019. Information on demographic characteristics was extracted from self-administered questionnaires. We investigated the association of LAN with standardized BMI using linear regression and with islet autoimmunity using generalized additive models, segmented regression and quartile analysis. All models were adjusted for sex, age, family history of diabetes and area-level socioeconomic status (SES). Results: The mean standardized BMI was 0.12 ± 1.04 and 225 children showed islet autoimmunity. A 10 nW/cm2/sr increase in LAN was significantly associated with a 2.14% increase in standardized BMI (95% confidence interval (CI): 0.86-3.45). Also, LAN exposure was linearly associated with a significantly higher odds of islet autoimmunity in children with exposure levels up to 11 nW/cm2/sr (Odds ratio (OR): 1.98; 95% CI: 1.14-3.45). Similar, quartile analyses showed a greater risk of islet autoimmunity especially for the third quartile (Q3: 5.2-11.6 nW/cm2/sr) of LAN compared to the lowest quartile (Q1: 0.0-2.0 nW/cm2/sr; OR: 1.71; 95% CI: 1.19-2.47). Conclusion: Exposure to LAN might be a further environmental risk factor contributing to higher BMI and islet autoimmunity in children. Keywords: Light at night, light pollution, body mass index, islet autoimmunity