Abstract: Objective: To examine the relationship between the obesity and the incidence of diabetes mellitus(DM) in Jiangsu Province. Methods: Through stratified cluster sampling, we investigated 8 734 inhabitants aged 20-88. Results: The results showed that the prevalence rate of obesity, DM, and IGT was 28.98%, 4.26%, and 5.30% in male, and 29. 81%, 6. 69%, 6. 29% in female. There was significant difference between both sexes in DM and IGT. The prevalence rate of DM, IGT in BMI≥25 male group was 2.45%, 3.30%, and 7.46%, 5.95% in female group. The prevalence of DM, IGT in having diabetes family history was 6. 50% and 4.46%. And there was a trend that the prevalence of DM, IGT increased with age. Conclusion: Obesity and correlative factors were risk factors of DM.