OBJECTIVE: We examined the distribution of diabetes and modifiable risk factors to provide data to aid diabetes prevention programmes in India. DESIGN: Population-based cross-sectional survey of men and women included in India's third National Family Health Survey (NFHS-3, 2005-2006). SETTING: The sample is a multistage cluster sample with an overall response rate of 98 %. All states of India are represented in the sample (except the small Union Territories), covering more than 99 % of the country's population. SUBJECTS: Women (n 99 574) and men (n 56 742) aged 20-49 years residing in the sample households. RESULTS: Prevalence of diabetes was 1598/100 000 (95 % CI 1462, 1735) among men and 1054/100 000 (95 % CI 974, 1134) among women in India. Rural-urban and marked geographic variation were found with higher rates in south and north-eastern India. Weekly and daily fish intake contributed to a significantly higher risk of diabetes among both women and men. Risks of diabetes increased with increased BMI, age and wealth status of both women and men, but no effects of the consumption of milk/curd, vegetables, eggs, television watching, alcohol consumption or smoking were found. Daily consumption of pulse/beans or fruits was associated with a significantly reduced risk of diabetes among women, whereas non-significant inverse associations were observed in the case of men. CONCLUSIONS: Prevalence was underestimated using self-reports. The wide variation in self-reported diabetes is unlikely to be due entirely to reporting biases or access to health care, and indicates that modifiable risk factors exist. Prevention of diabetes should focus on obesity and target specific socio-economic groups in India.