Relationship Between Triglyceride-Glucose Index and Handgrip Strength in the Midlife and Elderly Population: Evidence...

At present, only a limited number of studies have investigated the association between muscle strength and insulin resistance. This study aimed to investigate the relationship between handgrip strength, a recognized indicator of overall muscle function and healthy aging, and triglyceride-glucose (TyG)-based indicators, including the TyG index, TyG-body mass index (TyG-BMI), TyG-waist circumference (TyG-WC), and TyG-waist-to-height ratio (TyG-WHtR), among middle-aged and older Chinese adults.

We utilized a cohort from the China Health and Retirement Longitudinal Study (CHARLS) collected in 2011 and 2015, comprising a total of 3318 participants. Handgrip strength was assessed using absolute handgrip strength (measured by dynamometers), relative handgrip strength (absolute handgrip strength standardized by BMI), and defined weak handgrip strength. The relationships between the TyG index and its derived measures (TyG-BMI, TyG-WC, and TyG-WHtR) and different grip strength outcomes were examined using both multivariable logistic and linear regression approaches. To evaluate potential nonlinear patterns, restricted cubic spline (RCS) models were applied. Supplementary and robustness analyses encompassed receiver operating characteristic (ROC) curve evaluation, stratification by quartiles, subgroup comparisons, and handling of missing data via multiple imputation.

Between 2011 and 2015, 610 participants developed weak handgrip strength. Among all TyG indices, only TyG-WHtR was significantly associated with grip strength indicators (absolute: β = -0.95, 95% CI: -1.56 and -0.33; relative: β = -0.06, 95% CI: -0.09 and -0.03; weak: OR = 1.34, 95% CI: 1.03 and 1.74). These associations remained robust when using cumulative TyG-WHtR. K-means clustering identified three TyG-WHtR trajectory subgroups. Compared to the stable low group, both moderate (β = -0.10) and sharply increasing groups (absolute: β = -1.19; relative: β = -0.15) showed a greater risk of muscle decline. ROC curves indicated similar diagnostic accuracy for baseline and cumulative TyG-WHtR.

Higher TyG-WHtR levels appear to be independently linked to poorer handgrip strength performance in midlife and elder adults. Maintaining a low TyG-WHtR may contribute to improving the health status of midlife and elderly adults by preserving handgrip strength.