Abstract
BACKGROUND: The relationship between the TyG index and MASLD in lean young populations remains unclear. METHODS: In this retrospective study, we analyzed data from individuals aged 18 to 35 Years old who underwent abdominal ultrasound examinations at a healthcare management center from January 2019 to December 2023. First, we categorized the TyG index into quartiles and used logistic regression models to examine the relationship between MASLD and TyG. Next, we applied restricted cubic splines (RCS) to assess whether the relationship between TyG and MASLD followed a nonlinear pattern. Additionally, we stratified the analysis by sex to explore whether the association between MASLD and TyG differed between males and females. RESULTS: A total of 20,242 participants (14763 women [72.9%]; [mean ± SD] age, 29.07 [3.60]) were included in the study. The overall incidence of MASLD was 5.1%. The median (IQR) TyG index was 8.0 (7.6, 8.2). The association between TyG index and the incidence of MASLD followed a reverse L-shaped, with a cut-off value of 8.3. For each 1-unit increase in the TyG index, the association was significant both below 8.3 (HR = 2.1; 95%CI: 1.4-3.4 ) and above this threshold (HR = 12.1; 95%CI: 8.2-17.8). A significant interaction between sex and the TyG index was observed (P < 0.001). Both males and females showing an increase in MASLD risk after the TyG index exceeded 8.3. CONCLUSION: In young populations, higher TyG index is associated with an increased risk of MASLD, with distinct patterns observed between sexes. The risk of MASLD rises sharply once the TyG index exceeds 8.3.