Abstract: Objective To investigate the relationship bewteen weight control and the incidence of type 2 diabetes mellitus(T₂DM).Methods Non diabetic subjects were recruited from the program Prevention of Multiple Metabolic Disorders and Metabolic Syndrom(MS) in Jiangsu Province(PMM JS) to evaluate the incidence rate of DM in diferent weigth control groups.The relationship between we ight control and the subsequent development of T₂DM was evaluated with Coxratiohazard model.Results During the followup period, 102 subjects developed DM among 3168 study subjects.The incidence rate of DM inlean, normal weight, over weight, and obesity group was 3.4%, 4.1%, 5.5%, and 5.7%.The incidence rates of DM in the group with normal baseline weight and overweight but without weight control were 15.4%,7.2%, which were significantly higher than those who controlled weight during the followup period(4.9%).After adjusting for age, sex and other diabetes related risk factors at base line study and compared with the keeping normal weight group, the multivariable adjusted relative ratios(RRs)(95% confidence interval) for incident diabetes in the subjects with normal weight at baseline and then became obesity was 4.09(1.75-9.54).While in obese patients with uncontrolled weight was 2.89(1.54-5.42).Conclusion When the weight was effectively under control, the risk of developing T₂DM could be reduced.