Trajectories of triglyceride-glucose index changes and their association with all-cause and cardiovascular mortality: a competing risk analysis

Abstract Background The association between changes in insulin resistance, reflected by the triglyceride-glucose (TyG) index, and mortality remains unclear. This study investigated whether longitudinal trajectories of TyG index changes are associated with all-cause and cardiovascular disease (CVD) mortality. Methods This retrospective cohort study analyzed data from 233,546 adults aged ≥ 19 years from the Korea National Health Insurance Service-National Sample Cohort. Participants were categorized as having increasing, stable, or decreasing TyG index changes during a 4-year exposure period (2009–2014). Mortality outcomes were assessed during an 8.13-year follow-up period (2015–2021). Cox proportional hazards regression and competing risk analysis were used to evaluate all-cause and CVD mortality. Results A total of 7918 mortality events, including 651 CVD deaths, were recorded. Compared with the stable group, adjusted hazard ratios for all-cause mortality were 1.09 (95% CI 1.03–1.15) in the increasing group and 1.23 (95% CI 1.01–1.50) for CVD mortality. An increased TyG index was significantly associated with all-cause mortality in individuals aged < 50 years; men; and individuals with obesity, hypertension, diabetes, and/or dyslipidemia. For CVD mortality, significant associations were found in individuals aged 50–69 years, with obesity, with diabetes, or without dyslipidemia. Conclusion An increasing TyG index from baseline during follow-up was independently associated with higher risks of all-cause and CVD mortality. Serial monitoring of TyG index changes could enhance risk stratification and inform targeted interventions to reduce insulin resistance, and ultimately lower mortality risk.