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

Original Article

Austin J Clin Immunol. 2023; 9(1): 1054.

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

Dunjuan Shen¹; Lian Yang²; Mingyi Zhang³; Cuilan Zhang¹*; Xiaoyan Wang³**

1Department of Obstetrics and Gynecology, Nanjing Jiangning Hospital, The Affiliated Jiangning Hospital of Nanjing Medical University, Nanjing, Jiangsu, 211100, China

2Department of Medical Imaging, Nanjing Jiangning Hospital, The Affiliated Jiangning Hospital of Nanjing Medical University, Nanjing, Jiangsu, 211100, China

3Department of Clinical Laboratory, Nanjing Jiangning Hospital, The Affiliated Jiangning Hospital of Nanjing Medical University, Nanjing, Jiangsu, 211100, China

*Corresponding author: Xiaoyan Wang; Cuilan Zhang Department of Clinical Laboratory, Nanjing Jiangning Hospital, The Affiliated Jiangning Hospital with Nanjing Medical University, Nanjing, Jiangsu, 211100, China. Department of Obstetrics and Gynecology, Nanjing Jiangning Hospital, The Affiliated Jiangning Hospital with Nanjing Medical University, Nanjing, Jiangsu, 211100, China. Email: joyisme12@njmu.edu.cn; zcl591@126.com

Received: March 07, 2023 Accepted: April 27, 2023 Published: May 04, 2023

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.

Keywords: Blood glucose self-monitoring; Diet; Gestational diabetes mellitus; Second pregnancy trimester; Thyroxine; Triiodonine

Introduction

Gestational Diabetes Mellitus (GDM) and abnormal thyroid function are two common endocrine disorders occurring during pregnancy. During pregnancy, the size of the pregnant woman’s thyroid increases by 10-40%, and the production of thyroid hormone increases by approximately 50% [1]. However, pregnant women with GDM have a higher incidence of thyroid disease than healthy individuals [2,3]. Insulin resistance and changes in carbohydrate metabolism are related to abnormal thyroid function [4,5]. Blood glucose levels during pregnancy are affected by various physiological hormones, which in turn are affected by thyroid hormones [6]. Therefore, abnormal thyroid hormones during pregnancy increase the risk of GDM [7-10].

GDM can be controlled by diet or insulin. Poor blood glucose control in women with GDM is also associated with poor neonatal prognosis and perinatal outcome [11,12]. Women with GDM with good glycemic control do not have increased risks of adverse maternal or neonatal outcomes [13,14]. Therefore, the effect of GDM control is particularly important. However, the effect of abnormal thyroid function on the control of GDM remains unknown.

In this study, we evaluated the correlation between the levels of different thyroid hormones (free triiodothyronine [fT3], free thyroxin [fT4], and Thyroid-Stimulating Hormone [TSH]) with the control of blood glucose in pregnant women with GDM that was controlled by diet.

Materials and Methods

Study Population and Data Collection

This study was approved by the Ethics Committee of the Jiangning Hospital, Nanjing, Jiangsu Province. This study was performed in accordance with the principles of the Declaration of Helsinki. Written informed consent was obtained from each woman with GDM at screening, and the patients agreed that their clinical data would be used for research purposes. This is a retrospective study including women with GDM at their second trimester antenatal screening and who planned to deliver at the Nanjing Jiangning Hospital from January 2018 to December 2019. Patients meeting the following criteria were included: 1) a single pregnancy; 2) complete data of a 2-h 75-g Oral Glucose Tolerance Test (OGTT) until deliver; and 3) delivery in the Nanjing Jiangning Hospital. Patients meeting the following criteria were excluded: 1) Diabetes before pregnancy; 2) Polycystic Ovary Syndrome (PCOS); 3) Personal history of thyroid disease; 4) Goiter; 5) Taking hormone drugs affecting thyroid function before or during pregnancy; 6) Multiple pregnancy; or 7) Incomplete medical data.

The Medical data of patients were obtained from databases. Approximately 717 pregnant women diagnosed with GDM in a second trimester antenatal screening were initially included in this study, and the following patients were excluded: 5 patients with diabetes history, 11 with history of thyroid disease, 6 with a history of thyroid disease, 12 taking drugs affecting thyroid function, 4 cases of twins, 3 with PCOS, 82 without OGTT results, and 111 with an incomplete medical record. Ultimately, 439 GDM women were included. The participants were followed up until delivery. The characteristics of the study population are shown in a flow chart in Figure 1.