The association of the triglyceride-glucose index and its changes with 5-year all-cause mortality in patients with depression

Xiaojiao Cui¹Bo Xie²Yu-Fei Zhou²Xiaoqing Yi^1*

• ¹Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, China
• ²Chengdu First People's Hospital, Chengdu, China

Background: Depression is a leading cause of global disease burden, underscoring the need for prognostic biomarkers. The triglyceride glucose index (TyG), linked to insulin resistance and inflammation, may help predict outcomes in depression, though its long-term prognostic value remains unstudied. This research examines whether TyG levels and changes correlate with 5-year mortality in depressed patients. Methods: This retrospective cohort study used data from the MIMIC-IV database, including 1388 patients with depression. Of these, 1120 had one TyG measurement, and 268 had repeated measurements. The primary outcome was 5-year all-cause mortality. Analyses included restricted cubic splines, propensity matching, Cox regression, and Kaplan–Meier curves. Results: The overall 5-year mortality was 25.8% (358/1388). Multivariate Cox regression showed that higher TyG levels were associated with increased mortality risk (HR 1.31, 95% CI 1.10–1.56, p = 0.002). The highest TyG quartile had a 61% greater risk than the lowest (HR 1.61, 95% CI 1.15–2.25, p = 0.005). A linear dose-response relationship was observed (p-nonlinear >0.05). Kaplan–Meier analysis confirmed significantly higher mortality in high-TyG groups (p < 0.05). Changes in TyG over time (TyGVR) also linearly predicted mortality (p-nonlinear = 0.953). Subgroup analyses were consistent without significant interactions. Conclusions: The TyG index is positively and linearly associated with 5-year all-cause mortality in patients with depression. Monitoring TyG dynamics could enhance risk stratification for mortality in this population.