A cross-sectional population-based study of 2128 residents aged 40-69 years was carried out in 1995 to determine the prevalence of diabetes and the association of obesity and physical activity with this disease. Subjects were invited to the clinic for interview, physical and laboratory examination. Venous blood samples were taken fasting and 2 hours after a 75 g oral glucose load. Using the 1985 WHO criteria, the overall prevalence rate of diabetes and impaired glucose tolerance (IGT) were 30% and 18%, respectively. In the age group 50-59 years prevalence was 29% in men and 35% in women. Mean body mass index (BMI) was 27.3 kg/m(2) in men and 28 kg/m(2) in women. Only 13% of men and 1% of women walked at least 4 km/day. BMI was positively related to education and inversely related to physical activity. On average, subjects with diabetes were older, had higher monthly incomes and positive family history of diabetes. They also had higher mean BMI, waist-to-hip ratio (WHR), waist-to-height ratio (WHTR). Multiple logistic regression analysis shows that age, BMI (or WHR, WHTR), and less physical activity are independent risk factors of NIDDM. The prevalence of diabetes in Bahrain is increasing with economic development and changes from traditional to modernized lifestyle. Therefore, Bahraini people should attempt to retain certain features of their traditional lifestyle (physical activity, healthy eating, and moderate body weight).