Objective: To examine the impact for the UK population of providing statin treatment for diabetic patients for the primary prevention of coronary heart disease at a coronary event risk lower than currently recommended by the National Service Framework (NSF) for coronary heart disease. Design: Cross sectional survey. Setting: England 1998. Participants: Nationally representative sample of 6879 subjects aged 35-74 years living in private households. Main outcome measures: The proportion of the UK population recommended for statin treatment according to the NSF for coronary heart disease, and the proportion of the population with diabetes at a coronary disease event risk of ≥ 15% over 10 years. Results: Of the 6879 subjects with total cholesterol measurements, 218 (3.2%) had diabetes mellitus. In this nationally representative sample, 6.3% of the subjects (95% confidence interval (CI), 5.7% to 6.9%) were candidates for statin treatment for the secondary prevention of coronary heart disease, including 0.7% (95% CI 0.5% to 0.9%) with diabetes. A further 2.4% (95% CI 2.0% to 2.8%), including 0.4% (0.2% to 0.6%) with diabetes, were identified as candidates for primary prevention of coronary heart disease according to the NSF for coronary heart disease. Lowering the primary prevention threshold for statin treatment to a coronary event risk of ≥ 15% over 10 years in diabetic patients identified an additional 0.5% of the population. Conclusions: Extending statin treatment to diabetic patients at a coronary heart disease risk of ≥ 15% over 10 years would have a relatively small numerical impact in the UK population. Thus patients with diabetes mellitus should, as a minimum, be targeted for statin treatment at this level of risk.