Thyroid Function and Its Relation to Insulin Resistance in Women with Gestational Diabetes Mellitus (GDM) Compared with Healthy PregnantWomen

Gestational diabetes and hypothyroidism in pregnancy are the most common endocrine disorders which are considered as insulin resistant conditions. Maternal thyroid hormones play an important role in embryogenesis, fetal maturity, and child’s IQ level. It seems that subclinical hypothyroidism in women with gestational diabetes has a higher prevalence. Since thyroid function tests during pregnancy are not considered as part of a routine testing, therefore, we aimed to study thyroid function associated with insulin resistance in pregnant women. In this descriptive-analytic study, 142 pregnant women were randomly entered in GDM and normal groups. After obtaining demographic data and measuring all patients’ BMI, Glucose Tolerance Test (GTT) was performed. Serum insulin, thyroid function test and anti –TPO antibody were measured on fasting blood samples. Data were analyzed using descriptive statistics, T test, Chi-square test and multivariate regression analysis. 68 pregnant women with GDM and 74 normal pregnant women participated in this study. Patients with GDM had higher age and BMI (P< 0.0001). After eliminating the confounding variables, no significant correlation was found between TSH and insulin or HOMA-IR. Elevated anti-TPO was seen in 14.7% of GDM and 6.8% of normal women (P= 0.171). Significant correlation of anti TPO level was found between both insulin level (P= 0.01) and HOMA-IR (P=0.03). This study did not show any association between thyroid dysfunction and GDM. However, a higher anti-TPO level was seen in GDM patients. Further investigations with more sample sizes are recommended.