Central adiposity and sex influence lipid and glucose indices in Mexican adults: implications for metabolic risk assessment.

INTRODUCTION: Central adiposity is a major determinant of cardiometabolic risk. However, routinely used composite lipid-glucose indices are often interpreted to indicate a uniform metabolic signal across individuals with different body fat distributions. This study examined whether the interpretive behavior of the atherogenic index of plasma (AIP) and the triglyceride-glucose (TyG) index varies with central adiposity and the evaluated three-variant triglyceride-weighted genetic risk score (wGRS) in Mexican adults. METHODS: A cross-sectional analytical design was applied to data from 396 participants stratified by waist-to-height ratio (WHtR), incorporating correlation structure, an exploratory WHtR × wGRS interaction, and distributional analyses. RESULTS: Across WHtR tertiles, AIP was higher in the upper tertiles than in the lowest, with minimal additional separation between the intermediate and highest groups, and TyG showed the same upper-versus-lower tertile pattern. Sex-stratified predictions from the continuous interaction models showed that the absolute difference in AIP between wGRS levels of -1 SD and +1 SD narrowed from 0.91 to 0.15 z-score units in men and from 0.32 to 0.03 in women as WHtR increased from -1 SD to +1 SD. Distributional analyses revealed persistent within-stratum overlap, indicating metabolic heterogeneity despite similar anthropometric classifications. DISCUSSION: Identical AIP or TyG values may occur across different adiposity levels and degrees of wGRS-related separation within the evaluated population, supporting interpretation of these indices in relation to central adiposity.