Background Evidence regarding the impact of education on diabetes risk is scarce in developing countries. We aimed to explore the association between education and diabetes within a large population in China and to identify the possible mediators between them. Methods Information on educational level and lifestyle factors was collected through questionnaires. Diabetes was diagnosed from self-report and biochemical measurements. A structural equation model was constructed to quantify the mediation effect of each mediator. Results Compared with their least educated counterparts, men with college education had a higher risk of diabetes (odds ratio [OR] 1.19; 95% confidence interval [CI], 1.12-1.27), while college-educated women were less likely to have diabetes (OR 0.77; 95% CI, 0.73-0.82). Obesity was the strongest mediator in both genders (proportion of mediation: 11.6% in men and 23.9% in women), and its association with education was positive in men (beta[SE] 0.0387 [0.0037]) and negative in women (beta[SE] -0.0824 [0.0030]). Taken together, all behavioral factors explained 12.4% of the excess risk of diabetes in men and 33.3% in women. Conclusions In a general Chinese population, the association between education level and diabetes was positive in men but negative in women. Obesity was the major mediator underlying the education disparities of diabetes risk, with a stronger mediation effect among women.