The impact of the triglyceride-glucose index on the deterioration of kidney function in patients with cardiovascular-kidney-metabolic syndrome: insight from a large cohort study in China

The triglyceride-glucose (TyG) index has emerged as a credible surrogate indicator of insulin resistance in recent years. This study aimed to investigate the relationship between the TyG index and the deterioration of kidney function in patients with cardiovascular-kidney-metabolic (CKM) syndrome. In this retrospective cohort study from China, 27,407 hospitalized patients with stage 1–4 CKM syndrome were consecutively included. The participants were categorized into four groups according to TyG index quartiles. The study outcome was the deterioration of kidney function, defined as a decrease in estimated glomerular filtration rate (eGFR) ≥ 40% from baseline. Restricted cubic spline (RCS) curves and multivariate Cox analysis were used for analysis. 3,248 outcome events were recorded during a mean follow-up period of 34 months. The RCS plot displayed a U-shaped curve between the baseline TyG index and the deterioration of kidney function (<i>P</i> for non-linear &lt; 0.001). The baseline TyG index with the lowest hazard ratio (HR) of eGFR decline ranges from 8.65 to 9.15, with an inflection point at 8.88. After fully adjusting for covariates, HRs and 95% confidence intervals (CIs) from the lowest to highest TyG index quartile were 1.00 (reference), 0.82 (0.74, 0.91), 0.78 (0.70, 0.86), and 0.93 (0.83, 1.03), respectively. According to the Kaplan-Meier survival curve, the risk of deterioration of kidney function was elevated in the lowest and highest TyG index quartiles (log-rank test, <i>p &lt;</i> 0.0001). In individuals with CKM syndrome, a non-linear U-shaped relationship existed between the baseline TyG index and the deterioration of kidney function.