Lower TyG index but higher CVAI and fatty liver risk in high‑altitude overweight adults: a cross‑sectional study

The triglyceride glucose (TyG) index is a validated predictor of non-alcoholic fatty liver disease (NAFLD), but whether altitude modifies its predictive performance is unknown. We compared the TyG index, Chinese Visceral Adiposity Index (CVAI), and NAFLD prevalence between overweight adults at high (≥ 2500 m) versus low altitude (~ 500 m), and evaluated TyG’s predictive utility for NAFLD in each setting. We retrospectively studied 979 overweight adults (484 plateau, 495 plains). Their TyG index and CVAI were calculated, and NAFLD was diagnosed by ultrasound. The association between high-altitude residence and NAFLD has been assessed by multivariable logistic regression after adjusting for age and sex. The TyG performance has been evaluated by receiver operating characteristic curves. Compared to plains residents, high altitude residents had a lower TyG index (8.690 ± 0.567 vs. 8.947 ± 0.682, P < 0.001), but higher CVAI (118.0 ± 38.0 vs. 110.8 ± 36.6, P = 0.002) and greater NAFLD prevalence (74.1% vs. 67.1%, P = 0.017). Furthermore, high-altitude residence was an independent risk factor for NAFLD (adjusted OR = 1.60, 95% CI: 1.20–2.13, P = 0.001). TyG demonstrated acceptable and similar predictive performance in both groups (AUC ≈ 0.72), and optimal TyG cut-offs were 8.46 (plateau) and 8.69 (plains). Overweight adults at high altitude have lower TyG but paradoxically higher CVAI and NAFLD risk. TyG’s predictive ability is consistent across altitudes, but its absolute level requires altitude-specific interpretation. This study may provide an additional perspective to enhance NAFLD screening in high-altitude populations.