Parental education and occupation in relation to risk of childhood type 1 diabetes: nationwide cohort study

Background Socioeconomic status in the risk of developing type 1 diabetes seems inconsistent. We investigated whether risk of childhood-onset type 1 diabetes differed by parental education or occupation in a nationwide cohort. Methods This cohort study included all children born in Norway from 1974 to 2013. In individually linked data from nationwide population registries following children born in Norway up to 15 years of age, we identified 4647 with newly diagnosed type 1 diabetes during 15,381,923 person-years of follow-up. Results Children of mothers with a master’s degree had lower risk of type 1 diabetes than children of mothers with completed upper secondary education only: adjusted incidence rate ratio, aIRR=0.81 95% confidence interval: 0.69 - 0.95). There was no difference between upper secondary and lower secondary maternal education (aIRR=0.98, 95% confidence interval 0.89-1.08). Paternal education was not significantly associated with type 1 diabetes. While maternal elementary occupation was associated with a lower risk of type 1 diabetes, specific maternal- or paternal occupations were not. Conclusions Our results suggested inverse U-shaped associations between maternal socioeconomic status and risk of type 1 diabetes. Non-linear associations be part of the reason why previous literature has been inconsistent.