Combining triglyceride‑glucose index and novel anthropometric measures to predict mortality risk in patients with T2DM: a prospective cohort study

Insulin resistance, indicated by triglyceride-glucose (TyG) index, is thought to interact with obesity. Although recent studies have combined TyG with obesity measures to predict cardiovascular disease and mortality, few studies have incorporated novel anthropometric indicators, nor assessed these associations in diabetic populations. This study aims to assess whether TyG-related composite indices improve the prediction of all-cause mortality among elderly patients with type 2 diabetes mellitus (T2DM). Additionally, it seeks to explore the potential mediating role of renal dysfunction. We analyzed 307,161 individuals with T2DM aged over 60 years enrolled in the Shanghai Standardized Diabetes Management System from 2020 to 2024. Mortality outcomes were obtained by linking to the Shanghai Vital Statistics Registry up to 31 December, 2024. The association between TyG-related composite indices and all-cause mortality was examined using Cox proportional hazards models and restricted cubic splines. Two-piecewise Cox regressions were further developed for each side of the inflection point. Receiver operating characteristic curve analysis compared the predictive capacities of various indices. Mediation analysis was conducted to investigate the mediating effects of estimated glomerular filtration rate (eGFR). After a median follow-up period of 19 months, 14,536 (4.7%) deaths occurred. A U-shaped relationship was observed between five composite biomarkers and all-cause mortality. All composite indices outperformed the standalone TyG index, with TyG-a body shape index (TyG-ABSI) showing the highest prognostic efficacy. Notably, compared to the third quartile (Q3) of TyG-ABSI, hazard ratios (HRs) were 1.13 (95% confidence interval [CI] 1.08–1.19) for the first quartile (Q1) and 1.12 (95% CI 1.06–1.18) for the fifth quartile (Q5). Threshold analysis further identified an inflection point at 0.69, with HRs of 1.08 (95% CI 1.05–1.11) above and 0.85 (95% CI 0.81–0.89) below the threshold. Decreased eGFR mediated 24.3% of the association between the higher TyG-ABSI and increased mortality. TyG-ABSI exhibited superior prognostic accuracy for predicting all-cause mortality in elderly Chinese T2DM patients, following a U-shaped pattern. These findings underscore the importance of maintaining optimal TyG and visceral obesity levels and support the integration of TyG-ABSI into personalized risk management and public health strategies. Not applicable.