Dietary patterns, oxidative Stress, inflammation and biological variation in hemoglobin A1c: Association and Mediation analysis in a rural community in north China.

Objective: The aim is to assess the relationship between the hemoglobin glycation index(HGI) and dietary patterns, and investigates whether inflammation and oxidative stress mediate the relationship.

Methods: Cross-sectional data were collected from 453 dwellers in a Chinese rural community. Diet was assessed using 24 h food recalls. Based on the energy intake ratio from three macronutrients, dietary patterns were identified by cluster analysis. The HGI was defined as the observed HbA1c minus predicted HbA1c. Indicators of inflammation and oxidative stress were assessed.

Result: 3 dietary patterns were clustered, namely "fat(n = 100)", "balance(n = 186)" and "carbohydrate(n = 167)". The fat dietary patterns had lower HGI than the other two dietary patterns. TNFα was higher in the carbohydrate dietary pattern. Linear regression analysis suggested that the carbohydrate dietary pattern was correlated with higher HGI levels(β = 0.204,95 %CI(0.071,0.338)), compared with the fat dietary pattern. The relationship disappeared after accounting for biomarkers of inflammation and oxidative stress. Mediation analyses indicated that TNFα might explain for 19.15 % effects of the carbohydrate dietary pattern on HGI, compared with the fat dietary pattern.

Conclusion: The carbohydrate dietary pattern had positive associations with HGI and TNFα. TNFα partly mediated the relationship between dietary patterns and HGI.