We studied the prevalence of diabetes and impaired glucose tolerance (IGT) and their risk factors in the population of China. It was a population-based, cross-sectional study of 224,251 residents aged 25 years and over in 19 provinces and areas, including cities and rural areas of the North, South, East, West and central China. Using 1985 WHO criteria, We found the prevalence of diabetes and IGT were 2.51% and 3.20% respectively in 213,515 subjects aged 25 to 64 years. 70.33% of the subjects had newly recognised diabetes. The prevalence of diabetes in China is about 3 times higher than it was ten years ago, and the rate is increasing faster in the countryside than in cities. On average, subjects with diabetes are older, have higher personal annual incomes, and have more frequently a family history of diabetes. They also have higher mean body mass index (BMI), ratio of circumference of the waist to hip, systolic blood pressure, diastolic blood pressure and a greater prevalence of hypertension. They perform less physical activity and receive less education than persons with normal OGTT. Multiple logistic, stepwise regression analysis shows that age, BMI (or WHR), family history of diabetes, hypertension, less physical activity and higher annual income are independent risk factors of NIDDM, and that low education is also an independent risk factor of NIDDM in people with higher personal annual income.