Background: Macrosomia is a major adverse outcome associated with gestational diabetes mellitus (GDM), primarily driven by insulin resistance (IR). The triglyceride-glucose (TyG) index is a well-established surrogate marker for insulin resistance; however, its predictive value when combined with obesity indicators remains incompletely defined. This study aimed to compare the predictive performance of the TyG index and its derived indices during the second trimester for the risk of macrosomia in GDM. Methods: The TyG index, TyG body mass index (TyG-BMI), TyG waist circumference (TyG-WC), and TyG waist-to-height ratio (TyG-WHtR) were assessed at 24– 28 weeks of gestation. Their associations with macrosomia were analyzed using binary logistic regression and restricted cubic spline (RCS) analysis. The predictive performance of these indices was compared using receiver operating characteristic (ROC) curves, integrated discrimination improvement (IDI), and net reclassification improvement (NRI). The associations between TyG and its derived indices and the risk of delivering a macrosomic infant were further explored across different subgroups. Results: Logistic regression revealed that GDM women in the highest tertile had a 3.458- and 3.718-fold higher risks of delivering macrosomia compared to the lowest tertile for TyG-BMI and TyG-WC, respectively. RCS analysis showed a dose-response relationship (all P for overall < 0.001). Compared with the conventional TyG index, which had an area under the curve (AUC) of 0.596, both TyG-BMI (AUC = 0.682) and TyG-WC (AUC = 0.681) demonstrated significantly better performance ( P < 0.01); furthermore, their superiority was confirmed by significant IDI and NRI values ( P < 0.01). The association was more pronounced in primiparous women aged < 35 years ( P < 0.05). Conclusion: Elevated second-trimester TyG index and its derived indices are associated with an increased risk of macrosomia in GDM women. TyG-BMI and TyG-WC outperformed the conventional TyG index and may serve as valuable supplementary markers for early risk stratification in GDM. Keywords: gestational diabetes mellitus, insulin resistance, macrosomia, predictive model, triglyceride-glucose index
Chen et al. (Wed,) studied this question.