Understanding differences in how genetic susceptibility translates into diabetes risk between subgroups defined by lifestyle or health behavioural factors such as obese versus lean or sedentary versus active has the potential to inform strategies for disease prevention, as previously suggested for a common variant in the TCF7L2 gene in high risk individuals in the Diabetes Prevention Programme [20]. However, existing general population cohorts with prospective data on type 2 diabetes are underpowered to systematically investigate gene-lifestyle interaction. We have therefore set up the European InterAct Study whose nested case-cohort design combines the advantages of a prospective cohort with the efficiency and power of a large case-control study.
