The Triglyceride-Glucose Index Mediates the Association Between Obstructive Sleep Apnea and Non-Alcoholic Fatty Liver Disease: Findings From Two Cross-Sectional Datasets

Obstructive sleep apnea (OSA) contributes to non-alcoholic fatty liver disease (NAFLD) via pathways involving insulin resistance (IR). The triglyceride-glucose (TyG) index, a widely used marker of IR, is associated with both OSA and NAFLD. However, the role of the TyG index in linking OSA to NAFLD remains underexplored. This study analyzed data from two cross-sectional studies: 920 participants from the Fifth Affiliated Hospital of Sun Yat-sen University and 1,603 participants from NHANES 2005-2008. Mediation analysis assessed the TyG index's role in the OSA-NAFLD relationship. Weighted multivariable logistic regression and restricted cubic spline (RCS) regression explored the association between the TyG index and NAFLD in patients with OSA. Mediation analysis showed the TyG index mediated the OSA-NAFLD association, accounting for 35.33% and 20.06% in Chinese and American participants, respectively (P < 0.001). Logistic regression revealed that higher TyG index values were significantly associated with increased NAFLD risk in patients with OSA, with ORs of 2.32 (95% CI: 1.78-3.07) for Chinese and 6.80 (95% CI: 4.42-10.45) for American participants (P < 0.001). RCS regression showed a linear increase in NAFLD risk with higher TyG index values in patients with OSA. The TyG index significantly mediates the OSA-NAFLD relationship. Elevated TyG index values are significantly associated with NAFLD risk in patients with OSA. The TyG index is a biologically meaningful and effective biomarker of IR in the association between OSA and NAFLD, with potential for early identification of NAFLD in patients with OSA.