The triglyceride glucose index was U-shape associated with all-cause mortality in population with cardiovascular diseases

BACKGROUND: The triglyceride and glucose (TyG) index has been considered a simple surrogate marker of insulin resistance, related to a high risk of mortality. However, few studies have investigated the specific relationship between the TyG index and all-cause mortality among population with cardiovascular diseases. METHODS: 2,072 participants with cardiovascular diseases were enrolled from the National Health and Nutrition Examination Survey (NHANES) 1999–2014. The TyG index was calculated as log [fasting triglycerides (mg/dL) x fasting glucose (mg/dL)/2]. Outcomes were all-cause mortality and cardiovascular mortality. The baseline levels of TyG associated with the risk of mortality were evaluated on a continuous scale (restricted cubic splines) and by a priori defined quantile categories with Cox regression models. RESULTS: After a follow-up of 16.8 years, 791 all-cause deaths and 184 cardiovascular deaths occurred. Restricted cubic splines showed that the association between levels of TyG index and the risk of all-cause mortality was non-linear (p < 0.001) and the TyG index associated with the lowest risk of all-cause mortality ranges 8.83 to 9.06 in individuals with cardiovascular diseases. Compared with the reference quartile of 8.84 ~ 9.29, the multivariate-adjusted hazards ratios and 95% confidence intervals were 1.40 (1.13–1.74; p = 0.002) in the lowest quartile and 1.08 (0.88, 1.32; p = 0.475) in the highest quartile for all-cause mortality. However, TyG was not associated with cardiovascular mortality. CONCLUSIONS: TyG index was U-shape associated with the risk of all-cause mortality in participants with cardiovascular diseases and the level associated with the lowest risk ranged 8.83 to 9.06.