Persistently elevated TyG index trajectories and all-cause mortality risk in elderly adults in southwestern China: a prospective cohort study

Although previous studies have explored the association between the triglyceride-glucose (TyG) index and its trajectory with all-cause mortality in older adults, few have validated these associations specifically in the elderly population of southwestern China. This community-based prospective cohort study included 163,315 adults aged ≥ 65 years in Luzhou City, southwestern China. Participants were enrolled from the Luzhou Universal Preventive Health Examination Program between 2017 and 2024. TyG index trajectories from 2017 to 2019 were identified using Group-Based Trajectory Modeling (GBTM). Follow-up began from the end of physical examination for each study subject in 2019 and continue until December 31, 2024. Mortality data were collected to determine participants’ vital status. Multivariable Cox proportional hazards models, including restricted cubic splines (RCS), were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause mortality. The median follow-up time was 68.17 months, with 27,721 participants dying during the follow-up period. When the 2019 TyG index was divided into quartiles, after adjusting for confounding factors, the second quartile (Q2, HR : 1.00, 95%CI : 0.97–1.04, P = 0.913) and third quartile (Q3, HR : 0.99, 95%CI : 0.96–1.03, P = 0.694) were not associated with an increased risk of all-cause mortality compared with the first quartile (Q1). However, the fourth quartile(Q4, HR : 1.07, 95%CI : 1.03–1.11, P < 0.001) showed a significantly elevated risk. Results from RCS indicated a similar trend ( p for trend < 0.001). Four distinct trajectories of the TyG index were identified: low-growth ( n = 42,909, 26.27%), low-stability ( n = 86,249, 52.81%), medium-stability ( n = 26,727, 16.37%), and high-stability ( n = 7,430, 4.55%). Compared with the low-growth group, the risk of all-cause mortality in the low-stability group, medium-stability group, and high-stability group was 0.98 ( 95% CI : 0.94–1.01), 1.09 ( 95% C I: 1.05–1.13), and 1.24 ( 95% CI : 1.18–1.31), respectively. This study highlights that both a high baseline TyG index and a persistently elevated TyG trajectory are strongly associated with increased all cause mortality among older adults in southwestern China. Regular health check-ups and early interventions targeting elevated TyG levels may help promote longevity and improve health outcomes in this population.