Increased Central and Peripheral Thyroid Resistance Indices During the First Half of Gestation Were Associated With Lowered Risk of Gestational Diabetes—Analyses Based on Huizhou Birth Cohort in South China

• Published in: Frontiers in endocrinology (Lausanne) Vol. 13; p. 806256
• Main Authors: Liu, Zhao-min, Li, Guoyi, Wu, Yi, Zhang, Di, Zhang, Sujuan, Hao, Yuan-Tao, Chen, Weiqing, Huang, Qi, Li, Shuyi, Xie, Yaojie, Ye, Mingtong, He, Chun, Chen, Ping, Pan, Wenjing
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 08.03.2022
• Subjects: Birth Cohort; China - epidemiology; Diabetes, Gestational - epidemiology; Endocrinology; Female; gestational diabetes mellitus; Glucose; Humans; Longitudinal Studies; Pregnancy; prevention; thyroid; thyroid function tests; Thyroid Gland; thyroid hormone resistance index; Thyrotropin; Thyroxine; China; thyroid hormone resistance index; gestational diabetes mellitus; thyroid; prevention; thyroid function tests
• ISSN: 1664-2392; 1664-2392
• DOI: 10.3389/fendo.2022.806256

The study aimed to explore the relationship of thyroid function and resistance indices with subsequent risk of gestational diabetes (GDM). This was a longitudinal study embedded in the Huizhou Birth Cohort. A total of 2,927 women of singleton pregnancy were recruited from January to October of 2019. Thyroid central resistance indices were evaluated by Thyroid Feedback Quartile-Based index (TFQI), Thyrotrophy T4 Resistance Index (TT4RI), and TSH Index (TSHI) based on plasma-free thyroxine (FT4) and thyroid-stimulating hormone (TSH) levels during the first half of pregnancy. Thyroid peripheral sensitivity was assessed by free triiodothyronine (FT3) to FT4 ratio (FT3/FT4), a proxy of deiodinase activity. GDM was diagnosed between 24 and 28 weeks of gestation by a standardized 75 g oral glucose tolerance test. Multivariable linear and logistic regression was applied to examine the associations of thyroid markers with GDM risk. FT3 and FT3/FT4 were positively associated with both fasting and post-load glucose levels, while TSH, TSHI, TT4RI, and TFQI were negatively associated with 1 and 2 h post-load glucose levels. Compared with the lowest quartile, GDM risk in the highest quartile increased by 44% [odds ratio (OR) = 1.44; 95%CI, 1.08-1.92; = 0.027] for FT3 and 81% (OR = 1.81; 95%CI, 1.33-2.46; < 0.001) for FT3/FT4, while it lowered by 37% (OR = 0.63; 95%CI, 0.47-0.86; = 0.002] for TSHI, 28% for TT4RI (OR = 0.72; 95%CI, 0.54-0.97; = 0.06), and 37% for TFQI (OR = 0.63; 95%CI, 0.46-0.85; < 0.001). This longitudinal study indicated that higher FT3 and FT3/FT4 and lower central thyroid resistance indices were associated with increased risk of GDM.