A subcohort of 16,835 individuals was randomly selected from those with available stored blood and buffy coat, stratified by centre. We oversampled the number of individuals in the subcohort for the proportion of prevalent diabetes cases in each centre to account for later exclusion of individuals with prevalent diabetes from InterAct analyses. After exclusion of 548 individuals with prevalent diabetes, 129 individuals without information on reported diabetes status, and 4 individuals with post-censoring diabetes, 16,154 subcohort individuals were included in the analysis. Due to the random selection, this subcohort also included a random set of 778 individuals who had developed incident type 2 diabetes during follow-up.
