Objective To investigate the relationship between triglyceride-gluscose(TyG)index in early pregnancy and the delivery of small for gestational age infant(SGA)in patients with gestational diabetes mellitus(GDM).Methods A total of 1 532 pregnant women from Shanghai Fifth People's Hospital and the Second People's Hospital of Kashgar Region,who were enrolled in the study between Jan 2018 and Jun 2023 and met the inclusion criteria,were categorized into the group with GDM(754 cases)and the group without GDM(778 cases)based on the results of the oral glucose tolerance test(OGTT)conducted at 24-28 weeks of pregnancy.Within the GDM group,patients were further categorized into 3 groups based on neonatal weight:SGA group,large for gestational age infant(LGA)group,and appropriate for gestational age infant(AGA)group.A Logistic regression model was used to analyze the independent influences on SGA delivery in patients with GDM to analyze the correlation between the TyG index and the occurrence of SGA.The predictive value of the TyG index in early pregnancy for SGA delivery in GDM patients was analyzed using ROC curves.Results The TyG index in the SGA group of GDM patients was significantly lower than that in the LGA,AGA and control without GDM group(P＜0.05).Multifactorial logistic regression analysis revealed that the TyG index was independently correlated with the SGA in GDM patients(P＜0.05).The ROC curve analysis demonstrated a good predictive value of the TyG index in early gestation for SGA delivery in GDM patients(AUC=0.821,95%CI:0.763-0.879,P＜0.001).Conclusion The TyG index in early pregnancy among GDM patients is independently correlated with the occurrence of SGA infants and has a good predictive value for SGA delivery in GDM patients.