Dairy consumption, type 2 diabetes, and changes in cardiometabolic traits: a prospective cohort study of middle-aged and older Chinese in Beijing and Shanghai.

OBJECTIVE To prospectively investigate associations of dairy consumption with risk of type 2 diabetes and changes of cardiometabolic traits. RESEARCH DESIGN AND METHODS In 2005, 2,091 middle-aged and older Chinese men and women were recruited and followed for 6 years. Baseline dairy consumption was assessed by a 74-item food frequency questionnaire. Erythrocyte fatty acids were analyzed by gas chromatography coupled with flame ion detector. Cardiometabolic traits were measured at both baseline and follow-up visits. RESULTS Only 1,202 (57.5%) participants reported any dairy consumption, with a median intake of 0.89 (interquartile range 0.19-1.03) serving/day. Compared with nonconsumers, the relative risks (RRs) of type 2 diabetes among those having 0.5-1 serving/day and >1 serving/day were 0.70 (95% CI 0.55-0.88) and 0.65 (0.49-0.85), respectively, after multivariate adjustment (Ptrend < 0.001), which were attenuated by further adjusting for changes in glucose during follow-up (Ptrend = 0.07). Total dairy consumption was associated with favorable changes in glucose, waist circumference, BMI, diastolic blood pressure (all Ptrend < 0.05), and systolic blood pressure (Ptrend = 0.05) after multivariate adjustment, including baseline values of dependent variables. Erythrocyte trans-18:1 isomers were significantly correlated with total dairy consumption (rs = 0.37, Ptrend < 0.001), and these dairy food biomarkers were associated with a lower risk of type 2 diabetes. The RR of type 2 diabetes comparing extreme quartiles of trans-18:1 isomers was 0.82 (0.65-1.04, Ptrend = 0.02), which was attenuated after adjustment for dairy consumption (Ptrend = 0.15). CONCLUSIONS Dairy consumption was associated with a significantly lower risk of type 2 diabetes and favorable changes of cardiometabolic traits in Chinese.