Gestational Diabetes and Thyroid Autoimmunity

Abstract

Background. About 10% of pregnancies are complicated by previously unknown impairment of glucose metabolism, which is defined as gestational diabetes. There are little data available on prevalence of thyroid disorders in patients affected by gestational diabetes, and about their postgestational thyroid function and autoimmunity. We therefore investigated pancreatic and thyroid autoimmunity in gestational diabetic patients and in women who had had a previous gestational diabetic pregnancy. Methods. We investigated 126 pregnant women at the time of a 100-g oral glucose tolerance test: 91 were classified as gestational diabetics, and 35 were negative (controls). We also studied 69 women who had delivered a baby 18–120 months prior to this investigation and who were classified at that time gestational diabetics (38 women) or normally pregnant (31 women; controls). Results. Our data show no differences for both thyroid function and prevalence of autoimmune disorders during pregnancy; however, a significant increase in thyroid autoimmunity was seen in women previously affected by gestational diabetes. This increased prevalence of thyroid autoimmunity was not associated with the development of impaired glucose metabolism after pregnancy. Conclusions. Our data suggest that maternal hyperglycemia is a risk factor for the development of thyroid autoimmunity, a conclusion that should now be confirmed in a larger cohort of patients.

Thyroid dysfunction and autoimmunity in pregnant women with gestational diabetes mellitus: a cross-sectional study

“…In current study, women with gestational diabetes had normal TSH, but 10 % of them had free T 4 level below normal range. But in a study of Vitacolonna et al 15 there was no significant association between gestational diabetes and free T 4 level. Our data confirm the result of previous studies showing free T 4 level in women with diabetes mellitus type I significantly lower than healthy pregnant women.…”

“…In another study done by Vitacolonna and et al 15 reported, in case group, the average maternal age and BMI of 33 years old and 29.8 kg/cm 2 respectively, and the average maternal age and BMI of 29 years old and 28.1 kg/cm 2 respectively in control group.…”

“…16,17 Several studies showed no statistically significant difference in TSH serum level between gestational diabetes group and healthy group. 14,15,17,18 In a study by Karakosta et al conducted on 1170 pregnant women. In this study thyroid tests showed that presence of high level TSH and gestational autoimmune thyroid disorder increases risk of gestational diabetes up to 4 fold, and the risk of low birth weight up 3 times.…”

Assessment of the simultaneous effect of hypothyroidism and thyroid autoimmunity with gestational diabetes on the incidence of type 2 diabetes

“…Similarly, thyroid disorders, the most common endocrine disorders in women of childbearing age [2], are more prevalent in pregnant women with GDM, compared to their healthy counterparts [5]. Also, a signi cant increase in incident thyroid autoimmunity has been reported among women with a history of GDM (31.6% vs. 9.7%) [1]. It has also been shown that clinical and subclinical hypothyroidism is more common among women with T2DM, compared to non-diabetic women [6,7], e.g.…”

Evaluation of Thyroid Autoimmunity in Gestational Diabetes Mellitus

“…Several studies found a higher prevalence of thyroid autoimmunity in GDM compared to healthy controls; therefore they suggest that it would be appropriate to extend screening for thyroid diseases to women with GDM [10]. Higher prevalence of thyroid autoimmunity has been found in women who have had previous GDM and has been speculated that gestational hyperglycemia may trigger thyroid autoimmunity [11]. Some sudies have shown that instead of the presence of TPOAb, overt hypothyroidism causes an increase in the formation of diabetes mellitus [12].…”