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 population [9;10], potentially limiting the generalisability of our findings. Centre and country specific absolute incidence rates therefore need to be generalised and compared with caution. However, any bias due to differences in the case definition between countries would need to be consistent across centres and countries to lead a false positive association in our meta-analyses, the results of which also provide information about heterogeneity and hence to some degree generalisability of findings. The prevalence of important diabetes risk factors has changed since EPIC participants were recruited, with an ageing European population and greater prevalence of overweight and obesity; however, whether or not their relative importance for diabetes risk or potential interactions with genetic susceptibility has also changed remains unknown.
