Introduction: The two most prevalent endocrine conditions that can be seen during pregnancy are thyroid dysfunction and gestational diabetes (GDM). Changes in glucose metabolism and insulin resistance (IR) can both be linked to abnormalities in thyroid function. The study's objective was to ascertain whether pregnant women with gestational diabetes have aberrant thyroid hormone levels. Material and methods: The medical files of 662 pregnant women who gave birth between 2020 and 2022, separated into two groups: 412 with GDM and 250 with normal glucose tolerance. Using the International Federation of Gynecology and Obstetrics (FIGO) and American Diabetes Association (ADA) standards, a 2-h, 75-g oral glucose tolerance test (OGTT) was used to determine the presence of gestational diabetes mellitus in the study group. TSH, free thyroxine, free triiodothyronine, the FT3:FT4 ratio, fasting plasma glucose, age, and body mass index were all examined in both groups' mean blood concentrations. The Mann-Whitney U-test was used to compare the two groups. Results: Significantly greater TSH and FT3 concentrations (p 0.0001), lower FT4 concentrations (p 0.0001), and higher FT3:FT4 ratios (p 0.0001) were reported in patients who acquired GDM. Conclusion: According to the findings of this pilot retrospective series, high-normal to high TSH levels, low-normal to low FT4 levels, and a high FT3:Ft4 ratio may all point to an increased risk of developing GDM.