High adherence to the French dietary guidelines decreases type 2 diabetes risk in females through pathways of obesity markers: Evidence from the E3N-EPIC prospective cohort study

Objective

Obesity and type 2 diabetes (T2D) have been associated with low adherence to the 2017 French food-based dietary guidelines, as assessed by the Programme National Nutrition Santé - guidelines score 2 (PNNS-GS2). Whether the association between T2D and PNNS-GS2 is direct or mediated by obesity has been little investigated.

Research methods

The study included 71,450 women from the E3N-EPIC cohort, mean age of 52.9 y (SD 6.7). The simplified PNNS-GS2 was derived via food history questionnaire. Multivariable Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of T2D. Causal mediation analyses were used to decompose the total effect of sPNNS-GS2 on T2D into a direct effect and indirect effect mediated by body mass index (BMI) or the waist-hip ratio (WHR).

Results

During a mean follow-up of 19 y, 3679 incident T2D cases were identified and validated. There was a linear association between adherence to sPNNS-GS2 and T2D (P-nonlinearity = 0.92). In the fully adjusted model, each 1-SD increase in the sPNNS-GS2 was associated with a lower T2D risk [HR (95% CI), 0.92 (0.89, 0.95)]. The overall associations were mainly explained by sPNNS-GS2-associated excess weight, with BMI and WHR mediating 52% and 58% of the associations, respectively.

Conclusions

Higher adherence to French food-based dietary guidelines was associated with a lower risk of T2D in women, and a significant portion of this effect could be attributed to excess weight measured by BMI or WHR. This finding helps better understand the mechanisms underlying the diet-T2D association.