How were study participants identified?

People with diabetes were sought from 3 main sources: diabetes registers, trial databases and general practice. Hospital-based diabetologists and local GPs from around the UK were invited to collaborate by identifying potentially suitable individuals from their locally held diabetes registers. This approach has previously allowed large numbers of participants to be recruited by the Clinical Trial Service Unit into other studies such as the Heart Protection Study (HPS) and the Study of the Effectiveness of Additional Reductions in Cholesterol and Homocysteine (SEARCH), and is more efficient and cost-effective than mailings sent direct from individual centres or practices. Diabetologists and other collaborators were asked to identify local general practices with computerized diabetes registers, and to seek their agreement to invite potentially eligible individuals to participate.