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Abstract Objectives Our aim was to investigate the associations between dietary GI, CF and CQI and new-onset T2DM risk among Chinese adult. Methods Dietary glycemic index (GI), carbohydrate to fiber ratio (CF) and carbohydrate quality index (CQI) are conventional and emerging indicators for carbohydrate quality, respectively. Their associations with new-onset type 2 diabetes mellitus (T2DM) risk in Chinese adults remain unclear. We aimed to investigate the associations between dietary GI, CF and CQI and new-onset T2DM risk among Chinese adults. This prospective cohort study included 14,440 adults from the China Health and Nutrition Survey without cardiometabolic diseases at baseline. The associations between dietary GI, CF and CQI and T2DM risk were assessed using Cox proportional hazard regression analysis and dose–response relationships were explored using restricted cubic spline and threshold analyses. Results After a median follow-up duration of 9 years, a total of 1061 incident T2DM cases were identified. In fully adjusted models, higher dietary GI values were associated with reduced risk of T2DM, especially for Q4 (Q4 vs Q1: HR = 0.51; 95% CI: 0.38, 0.70; P-trend = 0.013), while CF and CQI were not significantly associated with incident T2DM. There were significant effect modifications of the association between dietary GI and T2DM risk by region and amount of carbohydrate intake (both P-interaction < 0.050). RCS analyses demonstrated significant non-linear trends of the associations between dietary GI and CF and T2DM risk (both P-overall < 0.001, P-nonlinear = 0.001), and threshold analyses showed that T2DM risk decreased and reached the bottom when dietary GI was 74.5 (73.4, 75.6) and CF was 27.3 (25.1, 29.6) (both P-log likelihood ratio < 0.001). Conclusions There were U-shaped relationships between dietary GI and CF and T2DM risk, indicating both dietary GI and CF should be controlled in a moderate range for T2DM prevention in Chinese adults. Further studies are required to confirm whether these indicators should be incorporated into dietary guidelines and Nutrient Facts panel labeling intended to help reduce T2DM risk in Chinese population. Funding Sources This study was funded by Shenzhen Science and Technology Program and the National Natural Science Foundation of China.