Is autoimmune thyroid dysfunction a risk factor for gestational diabetes?

Some recent studies have related autoimmune thyroid dysfunction and gestational diabetes (GD). The common factor for both conditions could be the existence of pro-inflammatory homeostasis. The study objective was therefore to assess whether the presence of antithyroid antibodies is related to the occurrence of GD.

Fifty-six pregnant women with serum TSH levels ≥ 2.5 mU/mL during the first trimester were retrospectively studied. Antithyroid antibodies were measured, and an O'Sullivan test was performed. GD was diagnosed based on the criteria of the Spanish Group on Diabetes and Pregnancy.

Positive antithyroid antibodies were found in 21 (37.50%) women. GD was diagnosed in 15 patients, 6 of whom (10.71%) had positive antibodies, while 9 (16.07%) had negative antibodies. Data were analyzed using exact logistic regression by LogXact-8 Cytel; no statistically significant differences were found between GD patients with positive and negative autoimmunity (OR = 1.15 [95%CI = 0.28-4.51]; P=1.00).

The presence of thyroid autoimmunity in women with TSH above the recommended values at the beginning of pregnancy is not associated to development of GD. However, GD prevalence was higher in these patients as compared to the Spanish general population, suggesting the need for closer monitoring in pregnant women with TSH levels ≥ 2.5 mU/mL.