BackgroundThe link between insulin resistance and endometriosis is not well established. The triglyceride-glucose (TyG) index serves as a straightforward and economical indicator of insulin resistance. This study examines the link between the TyG index and the prevalence of endometriosis in a U.S. cohort.MethodsThis cross-sectional study analyzed data from the NHANES conducted between 1999 and 2006. Reproductive health was assessed through questionnaires, and the TyG index was derived from fasting triglyceride and glucose measurements. Weighted logistic regression models were used to analyze the relationship between the TyG index and endometriosis. Restricted cubic spline (RCS) curves explored the linear relationship, while stratified and sensitivity analyses assessed potential interactions and the robustness of the findings.ResultsThe study included 2,346 women, with 176 diagnosed with endometriosis and 2,170 without. Women with endometriosis exhibited an elevated TyG index compared to those without the condition. The weighted logistic regression analysis revealed that the TyG index is an independent risk factor for endometriosis (OR = 1.58, 95% CI 1.17–2.14, p = 0.004). RCS analysis indicated a significant positive linear association between the TyG index and endometriosis, with a turning point at 8.51. Subgroup analysis indicated a stronger association in certain populations. The post-propensity score matching analysis confirmed the robustness of these findings.ConclusionIn the U.S. population, a higher TyG index is positively and linearly associated with endometriosis prevalence. Effective management of blood glucose and lipid levels may reduce the prevalence of endometriosis.