High Free T3 Levels in the Second Trimester are Correlated with the Control of Gestational Diabetes Mellitus

Abstract

Gestational Diabetes Mellitus (GDM) and abnormal thyroid function are two common endocrine disorders occurring during pregnancy. In this study, we evaluated the correlation between the levels of different thyroid hormones and blood glucose control in pregnant women with diet-controlled GDM. Mid-pregnancy serum samples were obtained from 439 participants with GDM controlled by diet for analyses of thyroid function. A 2-h 75-g oral glucose tolerance test was used to evaluate the effect of blood glucose controlled by diet. According to blood glucose levels before and 2h after a meal, mothers were grouped into GDM-A1 (≤5.3mmol/L, ≤6.7mmol/L, respectively) and GDM-A2 (>5.3 mmol, >6.7mmol/L, respectively) and these groups were compared to the associated thyroid levels using multivariate logistic regression analysis. Our results show that fT3 was positively associated with GDM-A2. The adjusted odds ratio (95% confidence interval) comparing the highest and lowest fT3 quartile was 3.12 (1.66, 15.87) at the second trimester. Neither TSH nor fT4 was significantly associated with GDM-A2. Higher FT3 levels during the second trimester of pregnancy are a risk for GDM-A2 incidence. This provides new ideas for the control of GDM.