The design of the intervention draws on successful pilots carried out in primary care clusters in North Ceredigion and Afan Valley. The evaluation of these pilots showed that there was a decrease in average blood sugar (glucose) levels between people receiving the brief intervention and their follow-up appointment, with a smaller number than expected going on to develop type 2 diabetes. The All Wales Diabetes Prevention Programme will be evaluated on an ongoing basis. Learning from the initial phase of the programme’s rollout will be used to optimise the programme as it develops over the coming years.