Association of triglyceride glucose-related obesity indices with sarcopenia among US adults: a cross-sectional study from the National Health and Nutrition Examination Survey

The triglyceride glucose (TyG) index-related obesity indices have been proposed as reliable indicators of insulin resistance. This study aims to investigate the association between TyG index-related obesity indices and sarcopenia as well as their potential as a tool for screening sarcopenic patients. A cross-sectional study was conducted involving 7,161 participants aged 18 and above from the National Health and Nutrition Examination Survey. TyG index and TyG index-related obesity indices, including triglyceride glucose-body mass index (TyG-BMI), triglyceride glucose-waist circumference (TyG-WC), and triglyceride glucose-waist-to-height ratio (TyG-WHtR) were determined using standard formulas. The ratio of appendicular skeletal muscle mass to BMI were used to assess sarcopenia. The relationship between the TyG index as well as TyG index-related obesity indices and sarcopenia was investigated using restricted cubic spline analysis and multivariate logistic regression analysis. The diagnostic value of the TyG index and TyG index -related obesity indices for sarcopenia was compared using the receiver operating characteristic (ROC) curve. In the fully adjusted regression model, a positive correlation was observed between the TyG-WHtR index and sarcopenia (for each one-unit increase in TyG-WHtR index: OR = 3.57, 95% CI: 2.71-4.71, P < 0.001). Additionally, regression analyses demonstrated TyG-WHtR as a significant predictor of sarcopenia with the highest odds ratio, reaching 12.50 (95% CI: 6.13-25.70, P < 0.001) for the upper fourth quartile (Q4) compared to the first quartile, followed by followed by TyG-BMI (Q4: 3.34; 95% CI: 1.92-5.80, P < 0.001) and TyG-WC (Q4: 1.95; 95% CI: 1.04-3.68, P < 0.001). The RCS curve fitting analysis indicated a U-shaped relationship between TyG-WHtR and the diagnosis of sarcopenia, with an inflection point at 4.02. Furthermore, in the ROC analysis, the AUC for the diagnosis of sarcopenia was largest for TyG-WHtR (0.79, P < 0.001). The TyG ndex-related obesity indices, especially TyG-WHtR, have been shown to be more effective in identifying sarcopenia patients than TyG alone.