Comparison of Thyroid Function Tests in Pregnant Women with and without Gestational Diabetes

Aim: The aim of this study was to determine whether there were abnormalities in thyroid hormone levels and anti-thyroid peroxidase antibodies in pregnant women with and without gestational diabetes mellitus. Material and Methods: We analyzed the medical records of 107 pregnant women. Clinical data related to maternal age, gestational week, body mass index, thyroid function tests, and anti-thyroid peroxidase antibodies, fasting blood glucose tests and HbA1c levels were obtained. The Pearson chi-square test, the Mann-Whitney U test, independent samples t-test, the Spearman correlation coefficient and Logistic regression model were performed. Results: Gestational diabetes mellitus group was significantly older (p=0.001). Body mass index was statistically different between the two groups (p=0.002). There were statistically significant differences in fasting blood glucose and HbA1c between the two groups (p<0.001 and p=0.004, respectively). The frequency of anti-thyroid peroxidase antibodies was higher in pregnant women with gestational diabetes mellitus, but the result was not statistically significant (p=0.716). Euthyroidism (57.9%) was more prevalent in all patients. While cases of subclinical hypothyroidism were statistically significantly different between gestational diabetes mellitus and non-gestational diabetes mellitus groups (p<0.001), euthyroidism and isolated hypothyroxinemia had no significant differences (p=0.093 and p=0.220, respectively). Our results suggest that pregnant women with subclinical hypothyroidism are 5.5 times more likely to be gestational diabetes mellitus. Conclusion: Subclinical hypothyroidism during pregnancy was detected more frequently in women with gestational diabetes mellitus than in women without gestational diabetes mellitus. Taken together, women with GDM should be performed thyroid tests and anti TPO routinely.