We examined the impact of a major pay-for-performance initiative introduced into UK primary care in 2004 on disparities in diabetes management between age, sex, and socioeconomic groups in this retrospective cohort study. We used data from the General Practice Research Database enrolling 422 family practices. Existing disparities in risk factor management (HbA1c, blood pressure, cholesterol) narrowed between men and women. Younger patients (<45 years) with diabetes appear to have benefited less from Quality and Outcomes Framework than older patients, resulting in some widening of existing age group disparities. Patients living in affluent and deprived areas appeared to have derived a similar level of benefit from pay for performance.