The triglyceride-glucose index is a predictor for cardiovascular and all-cause mortality in CVD patients with diabetes or pre-diabetes: results from the NHANES database prospective cohort study

Background: The association between the triglyceride-glucose (TyG) index and mortality in cardiovascular disease (CVD) patients with diabetes or pre-diabetes remains unclear. Therefore, the aim of this study was to explore the relationship between baseline TyG index and all-cause and cardiovascular (CV) mortality among American adults with CVD who have diabetes or pre-diabetes. Methods: : This study enrolled 1072 American adults with cardiovascular disease (CVD) and either diabetes or pre-diabetes, who participated in the National Health and Nutrition Examination Survey (2001-2018). Mortality outcomes were determined by linking to National Death Index (NDI) records up to December 31, 2019. The relationship between baseline TyG index and mortality in these patients was analyzed using Cox proportional hazards model and two-piecewise Cox proportional hazards model to explore potential nonlinear associations. Results: : During 7541 person-years of follow-up, a total of 334 all-cause deaths and 112 CVD-related deaths were recorded. The two-piecewise linear regression analysis revealed a U-shaped association between the baseline TyG index and all-cause and CVD mortality in CVD patients with diabetes or pre-diabetes. Specifically, a baseline TyG index lower than the threshold values (TyG index < 9.07 in all-cause mortality and < 8.92 in CVD mortality) was found to be negatively associated with mortality, with a hazard ratio (HR) of 0.48 (95% CI=0.28-0.83) for all-cause mortality and 0.43 (95% CI=0.08-1.41) for CVD mortality. In contrast, a baseline TyG index higher than the threshold values (TyG index > 9.07 in all-cause mortality and > 8.92 in CVD mortality) was positively associated with mortality, with a HR of 1.41 (95% CI=1.01-1.97) for all-cause mortality and 2.12 (95% CI=1.36-3.32) for CVD mortality. Conclusions: : A U-shaped association was observed between the baseline TyG index with CVD and all-cause mortality in CVD patients with diabetes or pre-diabetes in a American population. The thresholds of 8.92 and 9.07 for CVD and all-cause mortality, respectively.