Cumulative TyG-related indices in relation to incident arterial stiffness and carotid intima-media thickening: a 6-year follow-up within the 36-year Hanzhong adolescent hypertension cohort

Background Insulin resistance promotes both arterial stiffening and carotid atherosclerosis, but the comparative value of TyG-related indices for these phenotypes is unclear. Using a cohort with childhood anthropometry measured in 1987, we compared two vascular phenotypes, functional arterial stiffness (AS) and structural carotid intima–media thickening (cIMT), in relation to a common metabolic exposure, tested independence from early-life adiposity, and examined how the choice of exposure design (baseline, cumulative, or change) shaped these associations. Methods Within the Hanzhong Adolescent Hypertension Cohort (established 1987), we analysed 1,294 (incident AS) and 1,408 (incident cIMT) adults free of the respective outcome in 2017 and re-examined in 2023. Eight indices (TyG, TyG-BMI, TyG-WC, TyG-WHtR, TyG-WWI, TyG-BRI, TyG-CVAI, METS-IR) were modelled as baseline, cumulative, and 6-year change exposures. Incident AS was defined as brachial–ankle pulse wave velocity ≥ 1,400 cm/s, and incident cIMT thickening as mean cIMT ≥ 0.9 mm. Logistic regression, restricted cubic splines, and discrimination/reclassification metrics were applied, with additional adjustment for childhood (1987) BMI Z-score. Results Over 6 years, 296 (22.9%) and 464 (33.0%) participants developed AS and cIMT thickening. All eight cumulative indices were positively associated with both outcomes (all P < 0.05), with stronger associations for AS. TyG-WC showed the strongest AS association (OR per 1-SD 1.83, 95% CI 1.55–2.17; P < 0.001), whereas cIMT associations were modest (OR 1.17–1.24; all P < 0.05). The 6-year change exposure was largely not associated with incident cIMT thickening. Adding the indices to a conventional model improved discrimination for AS (ΔAUC 0.079–0.101; all DeLong P < 0.001) but only marginally for cIMT (ΔAUC 0.006–0.010). Estimates were unchanged after childhood-BMI adjustment and in sensitivity analyses. Conclusions Cumulative TyG-related indices, led by TyG-WC, were strongly related to incident arterial stiffness but only weakly to carotid intima–media thickening, independent of early-life adiposity. Long-term cumulative metabolic burden, rather than a single measurement or short-term change, better characterised vascular risk related to insulin resistance.