Background

The triglyceride-glucose (TyG) index has been proposed as an alternative to insulin resistance and as a predictor of cardiovascular outcomes. Little is known on its role in chronic stable cardiovascular disease and its predictive power at controlled low-density lipoprotein (LDL) levels.

Methods

Our study population consisted of 29,960 participants in the ONTARGET and TRANSCEND trials that enrolled patients with known atherosclerotic disease. Triglycerides and glucose were measured at baseline. TyG was calculated as the logarithmized product of fasting triglycerides and fasting glucose divided by 2. The primary endpoint of both trials was a composite of cardiovascular death, myocardial infarction, stroke or hospitalization for heart failure. The secondary endpoint was all-cause death and the components of the primary endpoint. Cox-proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for endpoints with extensive covariate adjustment for demographic, medical history and lifestyle factors.

Results

During a mean follow-up of 4.3 years, 4,895 primary endpoints and 3,571 all-cause deaths occurred. In fully adjusted models, individuals in the highest compared to the lowest quartile of the TyG index were at higher risk for the primary endpoint (HR 1.14; 95% CI 1.05-1.25) and for myocardial infarction (HR 1.30; 95% CI 1.11-1.53), but not for all-cause death (HR 1.10; 95% CI 0.99-1.21) or cardiovascular death (HR 1.08; 95% CI 0.95-1.24), stroke (HR 1.23; 95% CI 1.04-1.46) or heart failure hospitalization (HR 1.15; 95% CI 0.97-1.37).  A higher TyG index did not associate with the primary endpoint in individuals with an LDL <70mg/dl.  

Conclusion

A higher TyG index is associated with a modestly increased cardiovascular risk in chronic stable cardiovascular disease. This association is largely attenuated when LDL levels are <70mg/dl.