Triglyceride glucose index - body mass index predicts insulin resistance, metabolic syndrome and associates with impaired ovulation in Chinese women with polycystic ovary syndrome

Abstract

Background: Insulin resistance (IR) and metabolic syndrome (MetS) are highly prevalent and pathophysiologically central features of polycystic ovary syndrome (PCOS). However, their assessment is challenged by the limitations of gold-standard diagnostic methods. The clinical utility of the novel triglyceride glucose index - body mass index (TyG-BMI) for predicting IR, MetS, and its association with fertility outcomes in Chinese women with PCOS remains unexplored and warrants investigation. Objective: To evaluate the association between TyG-BMI and IR and MetS, and fertility outcomes in women with PCOS. Methods: We used data of 855 participants of the Acupuncture and Clomiphene for Chinese Women with Polycystic Ovary Syndrome (PCOSAct) trial. Linear trend tests and logistic regression evaluated relationships between TyG-BMI and anthropometric, hormonal, metabolic, and fertility outcomes. Receiver operating characteristic (ROC) curves assessed TyG-BMI’s predictive value for IR and MetS. RCS analysis was used to examine threshold effects between TyG-BMI and IR, MetS, and ovulation. A likelihood ratio test was further incorporated to validate the model fit. Results: TyG-BMI was positively association with IR (OR: 2.747, 95% CI: 1.942–3.887) and MetS (OR: 4.176, 95% CI: 2.278–7.653). TyG-BMI had a strong predictive performance, with AUCIR of 0.841 and AUCMetS of 0.899. For fertility outcomes, after adjusting for confounders, only ovulation showed a significant negative association (OR: 0.984, 95% CI: 0.973–0.994). The study revealed significant nonlinear associations between TyG-BMI and both IR and MetS, but a linear link with ovulation status. The inflection point occurred at a TyG-BMI of 203. Below this, IR risk increased progressively with TyG-BMI, plateauing above it. Above 203, MetS prevalence continued to increase, while ovulation rates declined inversely. Conclusion: Elevated TyG-BMI is strongly associated with worsened IR and MetS in PCOS women, serving as a practical screening tool for these conditions, while also demonstrating a potential negative impact on ovulation.