The relationship between the two endocrine pathologies: subclinical gestational hypothyroidism and gestational diabetes mellitus

BACKGROUND: Over the past decade, gestational diabetes mellitus has become of increasing medical and social importance. It happens due to its increased prevalence and due to its negative impact on pregnancy and long-term metabolic disorders in the mother and fetus.

AIM: The aim of this study was to assess the relationship between subclinical gestational hypothyroidism and gestational diabetes mellitus, the two most common endocrine pathologies in pregnancy.

MATERIALS AND METHODS: We studied 200 medical records of pregnant women. The main group included 133 patients with subclinical gestational hypothyroidism, and the control group consisted of 67 women without endocrine pathology. The diagnosis of gestational diabetes mellitus was made based on the Ministry of Health of the Russian Federation clinical guidelines criteria. The diagnosis of subclinical hypothyroidism was made based on the thyroid-stimulating hormone level above 2.5 μIU/ml in combination with an increased titer of antithyroid antibodies or above 4.0 μIU/ml in the absence of any thyroid disorder. Statistical analysis was carried out using the StatTech v.2.1.0 program (Stattech Ltd, Russia).

RESULTS: The prevalence of hypothyroidism was higher among women with family history of diabetes mellitus. The chances of developing gestational diabetes mellitus increased by 9.706 times in the presence of hypothyroidism, by 1.077 times with an increase in age by one full year at the time of seeing the doctor, and by 1.023 times with an increase in weight before pregnancy by one kilogram. The thyroid-stimulating hormone level of more than 2.7 μIU/ml predicted the development of gestational diabetes mellitus with a sensitivity of 71.4% and a specificity of 63.1%.

CONCLUSIONS: Subclinical gestational hypothyroidism and gestational diabetes mellitus are interrelated endocrine disorders with common pathophysiological predictors. Among women with a normal body mass index, subclinical gestational hypothyroidism is a more significant risk factor for gestational diabetes mellitus than an increase in age or body weight. A certain threshold level of thyroid-stimulating hormone (more than 2.7 μIU/ml) in the first trimester increases the chances of developing gestational diabetes mellitus and should be considered as a signal for timely prevention and detection of gestational diabetes mellitus.