Higher Ultraviolet Radiation During Early Life Reduces Risk of Childhood Type 1 Diabetes Among Boys

Abstract

Background: Ecological studies show an inverse association between type 1 diabetes incidence and ambient UV radiation (UVR) levels. We used large linked datasets to test ambient UVR during early life against type 1 diabetes risk at the individual level. Methods: We conducted a nested case-control study using linked data from state-wide administrative datasets. Cases (n=1819) were all children born in Western Australia from 1980-2014 with a diagnosis of type 1 diabetes on the Western Australian Children’s Diabetes Database between 0-16 years of age. Controls (n=27 259) were randomly selected from all live births in Western Australia and matched to cases on sex and date of birth. Daily UVR data from NASA satellites, that were date-and location-specific for each individual, were used to estimate total UVR dose for each trimester of pregnancy and the first year of life. Findings: Conditional logistic regression showed that type 1 diabetes risk was 44% lower in boys of mothers with UVR levels in the highest quartile (compared to the lowest quartile) during their third trimester of pregnancy (p=0·04). Higher UVR in the first year of life was also associated with a significantly lower risk of type 1 diabetes in later childhood among boys. Among girls, there was no evidence of associations between total UVR dose and type 1 diabetes risk. Interpretations: Higher UVR in the third trimester and first year of life appears to interact with sex-specific factors to lower type 1 diabetes risk among boys (but not girls) in Western Australia. Funding Statement: This research was supported by an Australian Government Research Training Program Scholarship and a PhD Top-Up scholarship from the Children’s Diabetes Centre, Telethon Kids Institute, Perth WA, Australia. The funding sources had no role in study design, data collection, data analysis, data interpretation, or writing of the report. The corresponding author had access to all the data and all authors agreed on the decision to submit for publication. Declaration of Interests: The authors have no conflicts of interest to disclose. Ethics Approval Statement: Use of these data was approved by the Western Australian Department of Health (2016/05) and the University of Western Australia Human Research Ethics Committee.