Evaluating the 2023 Mexican Dietary Guidelines for Type 2 Diabetes Prevention: A Target Trial Emulation in Mexican Women

In 2023, Mexico revised its Dietary Guidelines to promote healthy and sustainable diets, yet their impact on type 2 diabetes (T2D) prevention remains unexamined. We emulated a target trial within the Mexican Teachers Cohort to estimate the 9-year risk of T2D under an intervention adopting the Guidelines at baseline, compared to usual diet, using the parametric g-formula. Eligible participants were women aged ≥40 years without prior T2D, cardiovascular disease, or cancer between 2008-2010. Due to low baseline adherence to several components, we adapted thresholds so that ≥10% of the population met each recommendation. Incident T2D was identified through self-report or administrative data linkage. Among 11,307 eligible participants (mean age 46.0 years), 636 developed T2D over 9-years. The estimated 9-year risk of T2D was 8.44% (95% CI: 7.84, 9.12) under the usual diet and 7.11% (95% CI: 5.05, 9.82) under the intervention (risk ratio 0.84; 95% CI: 0.61, 1.15; risk difference -1.33 percentage points; 95% CI: -3.21, 1.29). These findings suggest a modest potential benefit if all participants had adhered to the adapted Guidelines at baseline compared with no intervention. The 95% confidence intervals indicate data are compatible with a small benefit, no effect, or a slight increase in risk.