Evaluating the impact of a national pilot screening programme for type 2 diabetes in deprived areas of England

Background. A pilot programme designed to systematically screen for type 2 diabetes was introduced in 24 general practices in England selected for their high levels of socio-economic deprivation and multi-ethnic populations. Objective. To evaluate the impact of screening on the prevalence of type 2 diabetes. Methods. A prospective audit of screening activity in pilot practices and comparison of the change in prevalence of diabetes in pilot and comparison practices were conducted. Results. Of 41 400 individuals invited for screening from a population of 165 828 in pilot practices, 25 356 (61%) were screened. Three hundred and fifty-eight (0.22%) new cases of diabetes were detected among those screened. Only 69% of those with a positive screening test had diagnostic testing recorded and only 19% had a record of an oral glucose tolerance test. The absolute increase in the prevalence of diagnosed diabetes was 0.53% in pilot practices and 0.42% in comparison practices. Conclusions. The 'real world' nature of the programme and dependence on routine data collection systems makes results more difficult to interpret but also enabled problems with implementation, not evident from previous research, to be identified. It is likely that the low diagnostic yield was largely due to a high level of ad hoc screening activity outside the pilot protocol and inadequate access to diagnostic testing after a positive screening test. In particular, implementation of screening for diabetes in primary care should not be undertaken without robust assessment of the resources required for diagnostic testing and follow-up and adequate clinical audit.