Thyroid disease and gestational diabetes mellitus (GDM): is there a connection?

The primary objective of this study is to assess for differences in incidence of gestational diabetes mellitus (GDM) for patients with thyroid hypofunction versus patients with thyroid hyperfunction.

A retrospective chart review of all women with clinical thyroid disease delivering at Johns Hopkins Hospital from January 2005 to December 2008 was performed. Clinical parameters were abstracted and appropriate statistical tests were performed.

GDM occurred in 12.3% of women in the study cohort. Of the women with hypothyroidism, 14.3% developed GDM compared to 5.8% of hyperthyroid women. Cesarean delivery was significantly higher in women with hypothyroidism versus women with hyperthyroidism (p = 0.002). There were no differences between groups with respect to preterm delivery, postpartum hemorrhage or hypertensive disorders of pregnancy.

If larger studies confirm the trends observed in our study, consideration should be given to including women with known thyroid disease in the subset of women who should be offered screening for diabetes early in pregnancy and appropriate clinical surveillance.