Non-linear association between the triglyceride-glucose index and all-cause and cardiovascular mortality in diabetes mellitus patients with hypertension: a retrospective cohort study

Abstract Objective The impact of the triglyceride-glucose (TyG) index on all-cause mortality and cardiovascular mortality in diabetes patients with hypertension remains unclear. The focus of this study was to investigate the relationship between the TyG index and mortality in in diabetes patients with hypertension. Methods This retrospective cohort study examined participants from the National Health and Nutrition Examination Survey (NHANES) between 2001 and 2018. Multivariable Cox regression models were used to estimate mortality risks. Restricted cubic spline (RCS) analysis was employed to assess the non-linear relationship between the TyG index and mortality risk. Stratified analyses and interaction tests were conducted based on gender, age, race, body mass index, smoking status, and the presence of cardiovascular disease. Results A total of 3,296 individuals were ultimately included in the study cohort. Over a median follow-up period of 82 months, 912 participants (27.7%) died from all causes, with 315 (9.6%) specifically attributed to cardiovascular disease (CVD). Following adjustment for potential confounders, the study revealed a non-linear association between the TyG index and mortality outcomes. Specifically, the relationship exhibited inflection points at 8.9 for all-cause mortality and 9.0 for cardiovascular mortality. The hazard ratios (HR) and 95% confidence intervals (95%CI) on the two sides of these inflection points were 0.85 (0.62, 1.16) and 1.38(1.14, 1.67) for all-cause mortality, and 0.70(0.44, 1.01) and 1.78(1.27, 2.48) for cardiovascular mortality. Stratified analyses revealed that among younger participants (aged 65 years), elevated TyG index levels were observed to have a significantly greater susceptibility to all-cause mortality HR = 1.69(1.20,2.39), p0.003, p for interaction = 0.01. Conclusion The TyG index shows a non-linear relationship with mortality risk in patients who have both diabetes and hypertension. The study found that all-cause mortality risk starts to increase when the TyG index exceeds 8.9, while the turning point for cardiovascular mortality risk is at 9.0. Additionally, elevated TyG index significantly correlates with increased all-cause mortality risk in younger patients (65).