There is little evidence involving the association between diet quality and the risk of diabetes among the Asian populations, especially from the long-term prospective cohort studies in China. This study evaluated the long-term diet quality of Chinese adults by the Chinese diet balance index 2016 (DBI-16) and firstly explored its role in diabetes prevention. A total of 9394 participants from the China health and nutrition survey (2004-2015) prospective cohort were included. Dietary information was selected by three consecutive 24-h dietary recalls, combined with a household food inventory and further calculated as the scores of the DBI-16 components and indicators. Three major indicators, the low bound score (LBS), the high bound score (HBS) and the diet quality distance (DQD), were divided into four level groups, according to the total scores, respectively, including Level 1 (scores below 20%), Level 2 (20-40% of scores), Level 3 (40-60% of scores) and Level 4 (scores above 60%). Diabetes cases were identified through a questionnaire or by testing the overnight fasting blood samples. Cox's proportional hazards models were used to estimate the hazard ratios (HRs) and 95% CIs, while restricted cubic splines (RCS) were applied to explore the potentially non-linear relationships. During a median follow-up of 6.0 years (61,979 persons-years), 657 participants developed diabetes. The LBS and DQD scores were positively associated with diabetes risks, whereas no significant association of the HBS scores with diabetes risks was observed. Compared with those on the lowest level, the adjusted HRs (95%) across the increased levels of diet quality were 2.43 (1.36, 4.37), 3.05 (1.69, 5.53) and 4.90 (2.46, 9.78) for the LBS; 1.06 (0.74, 1.51), 1.30 (0.99, 1.88) and 0.99 (0.39, 2.55) for the HBS; 1.28 (1.01, 1.61) and 2.10 (1.57, 2.82) for the DQD after pooling the participants on Level 1 and 2 as the reference group, due to the few who developed diabetics on Level 1 of the DQD. No significantly non-linear shape was observed for all three indicators. Our findings indicated a significant inverse association between the long-term diet quality assessed by the DBI-16 and diabetes risks, providing evidence for the positive role of healthy diets in diabetes prevention in Asia.
Keywords: CHNS; China health and nutrition survey; diabetes; diet balance index; diet quality.