Objective: During pregnancy, sonographic measurements of subcutaneous adipose tissue may be a reliable diagnostic predictor of gestational diabetes mellitus (GDM) and fetal metabolism. A sonographic view of the fetal abdominal circumference can be used to measure the fetal anterior abdominal wall thickness (AAWT), which is straightforward and simple. Consequently, in this study, the aim was to evaluate whether the fetal AAWT value could be used as a diagnostic indicator of GDM, thus preventing the adverse neonatal and maternal outcomes thereof, including shoulder dystocia, neonatal hypoxia, and injury to the birth canal, secondary to fetal macrosomia. Materials and Methods: This prospective cross-sectional study was conducted at a hospital in Lahore, Pakistan, over a 9-month period. A total of 176 female participants in their third trimester of pregnancy were included in this study. The participants were assigned to two cohorts: a cohort of 88 participants diagnosed with GDM and a control cohort of 88 participants without GDM. An independent sample t test, analysis of variance, and chi-square test were used to compare the characteristics between the two cohorts of participants. A final analysis was performed to determine the strength of the correlations between the estimated fetal weight (EFW) and AAWT values. Results: The GDM and control cohorts had mean fetal AAWT values of 12.65 ± 1.276 and 6.389 ± 1.503, respectively. Thus, a statistically significant difference in the fetal AAWT values was observed between the GDM and control cohorts. Furthermore, a statistically significant positive correlation between the EFW and AAWT values was observed ( P = .01). Conclusion: This study highlighted that women with GDM have a considerably higher fetal AAWT values than those without GDM. In addition, the findings revealed that the AAWT value was correlated with the EFW value. Consequently, an increased fetal AAWT value can potentially be utilized as a predictive indicator for those pregnant women at risk of developing GDM, thus preventing adverse maternal and fetal outcomes.