To assess the risk of gestational diabetes mellitus (GDM) according to the triglyceride and glucose (TyG) index values during the first trimester of pregnancy in Latin American women. Pregnant women were enrolled at their first prenatal visit at the Obstetric Division in the University Hospital "Dr. José E. González". Triglycerides and fasting plasma glucose (FPG) were collected to determine the TyG index. GDM diagnosis was performed by a single-step 2-hour 75-g oral glucose tolerance test. Generalized linear models were used to determine risk ratios; pregnancy outcomes at delivery were collected from the hospital medical records. A total of 164 pregnant women were included. GDM was present in 29 (17.7%) women. No significant differences in age, first-trimester body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters), family history of diabetes, and TyG index were observed between GDM cases and the reference group without GDM. The adjusted analysis showed no association between TyG and GDM (risk ratio [RR] 1.03, 95% confidence interval [CI] 0.57-1.88]). Higher TyG index values between women with and without a diagnosis of GDM in the second trimester were observed. No significant differences were identified in pregnancy outcomes, although a trend was observed for hyperbilirubinemia in women with first-trimester TyG index values greater than 8.7. Our findings do not support the use of the TyG index for GDM prediction in Latin American women.