Assessment of Thyroid Dysfunction Among Pregnant Women With Pre-Existing Diabetes Mellitus or Gestational Diabetes Mellitus

Objective This study investigates the prevalence and risk of thyroid disturbances in pregnant women with pre-existing diabetes mellitus (DM) or gestational diabetes mellitus (GDM) in a tertiary hospital setting in Riyadh, SA. This research's findings may help identify potential risk factors associated with thyroid disturbances during pregnancy and facilitate early diagnosis for at-risk pregnant women. Subjects and methods A retrospective cross-sectional study was conducted at an endocrinology clinic between October 2018 and December 2021 to evaluate the electronic records of pregnant women with DM or GDM who had documented normal thyroid function before pregnancy. Results Three hundred ninety-six files that met the selection criteria were deeply investigated and analyzed. The analysis showed that 378 (95.5%) patients were of Saudi nationality, and the mean age in years ± SD for the selected patients was 34.23 ± 5.468. The prevalence of obesity was 63.7%, with a mean body mass index (BMI) of 32.78 ± 6.78 kg/m2. The patients in this study were categorized into three groups based on their type of DM: 57 were diagnosed with type 1 DM (14.4%), 120 with type 2 DM (30.3%), and 219 with GDM (55.3%). The study identified 43 patients (10.85%) with subclinical hypothyroidism and 74 (18.69%) with hypothyroidism. Among the remaining patients, thyroid function was within the normal range for 264 (66.67%). The study also identified eight patients (2.02%) with subclinical hyperthyroidism and seven (1.77%) with hyperthyroidism. The prevalence of thyroid dysfunction was reported at 33.4%, with most of the dysfunction observed in the GDM group (20.7%). By comparison, the type 1 DM and type 2 DM groups presented a lower prevalence of thyroid dysfunction, accounting for only 4.1% and 8.6%, respectively. Conclusions Hypothyroidism, both clinical and subclinical, is more prevalent among patients with GDM than individuals with type 1 and type 2 DM. Research suggests a greater risk of developing hypothyroidism in patients with an increased BMI and among those older during pregnancy.