Thyroid dysfunction during gestation and gestational diabetes mellitus: a complex relationship

Abstract

Purpose Gestational diabetes mellitus (GDM) and thyroid dysfunction during gestation (GTD) are the two most prevalent endocrinopathies during pregnancy. The aim of the present review is to provide an overview of the peculiar aspects of GDM and GTD, to highlight the potential interactions and clinical consequences of these two frequent clinical conditions. Methods A literature review regarding GDM and GTD was carried out with particular interest on meta-analyses and human studies dealing with the (i) shared risk factors between GDM and GTD, (ii) the epidemiological link between GTD and GDM, (iii) physiopathologic link between GTD and GDM, (iv) clinical consequences of GDM and GTD, and (v) post-partum implications of GDM and GTD. Results The association between GDM and GTD is common and may be explained by the insulin-resistance state due to maternal GTD, to alterations in the placentation process or to the many shared risk factors. Discrepant results of epidemiologic studies can be explained, at least in part, by the changes in diagnostic criteria and screening strategies throughout the years for both conditions. GDM and GTD impact pregnancy outcome and have post-partum long-term consequences, but more studies are needed to prove an additional adverse effect. Conclusions Based on the epidemiological and physio-pathological link between GDM and GTD, it could be suggested that a diagnosis of GTD could lead to screen GDM and the other way round.

The expression of deiodinase 2 and deiodinase 3 are reduced by insulin and D-glucose respectively, in human placental explant cultures

“…Moreover, we noted that insulin favored both DIO2 and DIO3 protein expression in syncytiotrophoblast. Considering the epidemiological and physio-pathological link between insulin resistance and impaired thyroid function [34], plus the evidence showed in the present study, we suggest that a diabetogenic state, with high insulin and D-glucose levels, regulates deiodinase expression/activity and thus may promote fetal TH dysfunction. As a limitation of this study we identify that working with rst trimester explants would have been more representative of TH transport through developing placenta than third trimester explants.…”

Free triiodothyronine (FT3)-to-free thyroxine (FT4) ratio identified as a risk factor for gestational diabetes in euthyroid pregnant women: insights from a Chinese population cohort study

“…Some studies have shown that thyroid disease and GDM could share some common risk factors, such as age, BMI, vitamin D deficiency, selenium level and so on ( 26 ). Additionally, our study identified parity, BMI, blood pressure, blood lipid, UA, and HbA1c levels as independent risk factors for GDM, confirming the findings of earlier studies ( 27 , 28 ).…”

Gestational diabetes – management strategies including pharmacological treatment and lifestyle interventions

“…What is more, these thyroid dysfunctions including hypothyroidism and presence of thyroid antibodies in the blood may be starting points for GDM development due to the imbalances in glucose metabolism and insulin resistance. [17] According to growing evidence, GDM complicates 40 % of polycystic ovary syndrome (PCOS) pregnancies, suggesting that PCOS may be a risk factor for GDM. PCOS predisposes to the development of GDM due to the fact that it is often associated with obesity, dyslipidemia and metabolic disorders such as hyperinsulinemia and insulin resistance.…”