BACKGROUND AND AIMS: The triglyceride-glucose (TyG) index has emerged as a powerful and accessible marker of insulin resistance and a predictor of adverse events in patients undergoing percutaneous coronary intervention (PCI). Yet, its prognostic relevance in large, demographically diverse populations remains unestablished. This study sought to evaluate the association between the TyG index and clinical outcomes in a broad cohort of patients undergoing PCI at a high-volume tertiary care center in the United States. METHODS: We included consecutive patients undergoing PCI from 2012 to 2022. Quartiles of the TyG index, calculated as Ln(fasting triglycerides × fasting glucose/2), were derived and patients were stratified accordingly. The incidence of major adverse cardiovascular events (MACE), consisting of all-cause mortality, myocardial infarction (MI), or stroke, was assessed at 1 year. Multivariable Cox regression analyses were performed using the lowest TyG quartile as the reference. RESULTS: A total of 21 124 patients were enrolled. Those with higher TyG index values were more likely to be female and to have cardiovascular risk factors or comorbidities. They also exhibited a greater extent of coronary artery disease (CAD) and more complex PCI features, while showing a lower prevalence of moderate-to-severe coronary calcifications. At 1 year, MACE incidence increased progressively across quartiles, with the highest risk observed in the fourth quartile compared with the first. After multivariable adjustment, this association remained significant and was primarily driven by spontaneous MI. CONCLUSION: In this large PCI cohort, the TyG index correlated with adverse cardiovascular outcomes, supporting its potential role in clinical practice.