Although the possibility of examining the consistency of main genetic and interaction effects across the 8 European countries will help to understand factors contributing to any potential heterogeneity, results from our European descent InterAct participants do not allow inference about other ethnic groups with different allele frequencies and distribution and determinants of health behaviours. We used a clinical definition of type 2 diabetes that did not rely on glucose measurement. This means that although our case definition is specific due to the verification process, InterAct rates reflect the incidence of clinical type 2 diabetes and our case number would be even larger had it been possible to identify undiagnosed diabetes cases. Likewise, we have not ruled out undiagnosed diabetes in the subcohort, which may lead to an underestimation of main effects and reduced power for interaction analyses. Despite great efforts to standardise the clinical case definition of our study, some heterogeneity exists between centres due to differences in the information that was available locally for case ascertainment and verification. In addition, not all EPIC cohorts recruited participants from the general
