Environmental Determinants of Type 1 Diabetes: From Association to Proving Causality

The rising incidence of type 1 diabetes (T1D) cannot be ascribed to genetics alone, and causative environmental triggers and drivers must also be contributing. The prospective TEDDY study has provided the greatest contributions in modern time, by addressing misconceptions and refining the search strategy for the future. This review outlines the evidence to date to support the pathways from association to causality, across all stages of T1D (seroconversion to beta cell failure). We focus on infections and vaccinations; infant growth and childhood obesity; the gut microbiome and the lifestyle factors which cultivate it. Of these, the environmental determinants which have the most supporting evidence are enterovirus infection, rapid weight gain in early life, and the microbiome. We provide an infographic illustrating the key environmental determinants in T1D and their likelihood of effect. The next steps are to investigate these environmental triggers, ideally though gold-standard randomised controlled trials and further prospective studies, to help explore public health prevention strategies.

Automated summary

This review highlights the importance of environmental factors in the development of type 1 diabetes (T1D), focusing on infections, growth and obesity in infancy, the gut microbiome, and lifestyle choices. Evidence suggests that enterovirus infection, rapid weight gain in early life, and the microbiome are the most significant environmental determinants of T1D. Future research should explore these triggers further through randomized controlled trials and prospective studies to aid in the development of public health prevention strategies.