We studied cardiovascular risk factors in 149 rural, 142 slum dwellers, and 150 urban middle class Indian men (30 to 50 years, mean 40 years) in relation to their body fat. Mean body mass index (BMI) was 21.0, 22.3, and 24.3 kg/m2 and mean body fat percent (bioimpedance) was 20.4, 22.5, and 30.4, respectively. A 75 g oral glucose tolerance test showed no diabetes in rural subjects; 4% of urban slum dwellers and 10% of urban middle class men were diabetic. Hypertension (blood pressure > or = 140/90 mm Hg) was present in 2% of the rural, 4% of the urban slum, and 10% of the urban middle class men. All cardiovascular risk factors were strongly related the percentage of body fat and waist to hip ratio. Two hour plasma glucose concentration and blood pressure were, in addition, independently related to geographical location (urban middle class were higher than slums who were higher than rural men). Our results suggest that urbanization increases the risk of hyperglycemia and hypertension independent of the percentage of body fat or its central distribution.