Diet Quality Is Linked to Insulin Resistance among Adults in China

Background: Little is known about the impact of Chinese diet quality changes on diabetes-related markers. Objective: The present study examined the association of changes in overall diet quality with various biomarkers of diabetes among adults in China. Methods: The current analysis used longitudinal diet data from 1991 to 2006 and fasting blood samples from 2009 for 4734 adults aged 18-65 y from the China Health and Nutrition Survey. Dietary intake was assessed by using 3 consecutive 24-h recalls and household food weighing. The tailored Alternative Healthy Eating Index (tAHEI) was adapted from the 2010 Harvard Alternative Healthy Eating Index to measure overall diet quality. We categorized baseline tAHEI scores into tertiles and annual changes in the scores into 5 levels (high decrease, low decrease, maintain, low increase, and high increase). We performed mixed-effects regressions to assess the associations between baseline scores and changes in the tAHEI scores and diabetes or insulin markers. Results: Adults with high baseline tAHEI scores tended to be male, older, of lower socioeconomic status, and with higher physical activity levels. After adjustment for all of the covariates, insulin and homeostasis model assessment of insulin resistance (HOMA-IR) values were 5.1% (95% CI: -0.100, -0.002) and 5.7% (95% CI: -0.113, -0.001) lower, respectively, for adults with high compared with low baseline tAHEI scores and 8.6% (95% CI: -0.155, -0.017) and 9.8% (95% CI: -0.177, -0.018) lower, respectively, for adults with a high increase in score compared with the maintain category. Null associations were observed between baseline scores and changes in the scores and fasting blood glucose, glycated hemoglobin (HbA1c), and diabetes prevalence. Conclusions: Baseline and changes in diet quality were independently associated with lower HOMA-IR and plasma insulin but not with fasting blood glucose and HbA1c in Chinese adults. Prospective studies on overall diet quality in relation to diabetes markers and risk of diabetes are needed.