Aggregated data from Manchester practices participating in the Diabetes 2000 project were used to develop peer group standards of mean performance and of excellence. The crude prevalence of known diabetes mellitus was 1.21% of which 20.2% had Type 1 diabetes. The aggregated mean of patients who had the following examinations performed in the preceding year were: glycated haemoglobin 56.8%; weight or body mass index 67.8%; foot pulses 37.3%; ankle reflexes 31.3%; proteinuria 60%; fundoscopy 48.2%; blood pressure 81.1%; serum cholesterol or lipids 34%. The percentage of patients referred to or seen by health care professionals in the preceding year were 14.4% to diabetes specialist nurses; 22.1% to opticians or ophthalmologists; 25% to chiropodists; and 21.5% to dietitians. The best performing practices examined 79% of patients fundi in the preceding year, 84% of their foot pulses, 74% of their ankle reflexes, and gave appropriate smoking advice in 65% of cases. These standards were fed back to the participating practices so that they could compare their own performance with that of the city-wide mean, and with the best performing practices. From these data practices have then been able to set themselves realistic targets for improved performance in the following year.