Association of Triglyceride–Glucose Index and Coronary Chronic Total Occlusion in Patients Undergoing Coronary Angiography: A Retrospective Study

Background: The triglyceride–glucose (TyG) index is a simple surrogate marker of insulin resistance (IR) and has been associated with coronary artery disease (CAD). However, the association between the TyG index and coronary chronic total occlusion (CTO) remains limited. Methods: In this retrospective study, 1157 patients who underwent coronary angiography at Beijing Chaoyang Hospital from January 2024 to January 2026 were enrolled and classified into the CTO group (n = 317) and the non-CTO group (n = 840). Multivariable logistic regression analyses were performed to assess the association between the TyG index and CTO. Restricted cubic spline analysis was used to examine the linear dose–response relationship. Subgroup analyses were conducted according to age, sex, smoking status, hypertension, and diabetes mellitus. Results: Patients with CTO had a significantly higher TyG index than those without CTO (8.98 [8.46, 9.45] vs. 8.79 [8.41, 9.26], p = 0.003). In the multivariable logistic regression analysis, the TyG index was independently associated with the presence of CTO (OR = 1.377, 95% CI 1.082–1.752, p = 0.009). In a sensitivity analysis further adjusted for diabetes mellitus, the association remained significant (OR = 1.356, 95% CI 1.052–1.747, p = 0.018). Restricted cubic spline curve analysis showed a nonlinear dose–response relationship (p for nonlinear = 0.005) between the TyG index and CTO risk. In the subgroup analyses, the association was directionally consistent across subgroups. Nominally significant associations were observed in elderly participants (OR 1.68, 95% CI 1.20–2.37, p = 0.003), men (OR 1.40, 95% CI 1.06–1.86, p = 0.018), and patients with hypertension (OR 1.55, 95% CI 1.14–2.11, p = 0.005). Conclusions: An elevated TyG index was independently associated with the presence of CTO. The association was generally consistent across major clinical subgroups, with no significant interactions observed.