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.