Gestational diabetes mellitus (GDM)—carbohydrate intolerance that begins or is first recognized during pregnancy—carries increased risk for the mother, fetus, and newborn infant. Both impaired insulin secretion and increased resistance to insulin have been described in GDM. Short-term exogenous corticosteroids can derange glucose metabolism when given alone or with beta-adrenergic drugs, but little is known about whether long-term steroid treatment adversely affects glucose tolerance during pregnancy. This case-control study compared 25 pregnant women with idiopathic thrombocytopenic purpura (ITP) who received steroids (5–10 mg daily of prednisone) for longer than 4 weeks with 108 pregnant women who had not received steroids. Women having pregestational diabetes were excluded. The two groups were similar with regard to age and body mass index.
Steroids had been given to the ITP group for nearly 10 weeks on average, and the duration of treatment correlated positively with the risk of the development of GDM which was diagnosed in 24% of steroid-treated women, and in 3% of control women. Subsequent diabetes also was more prevalent in steroid-treated women. With one exception, GDM was diagnosed by screening at 16 weeks' gestation. Five of six affected study patients but none of three control women with GDM required insulin. Target blood glucose levels were achieved in all diabetic women and there were no acute metabolic complications. All the ITP pregnancies resulted in a live birth. Only one infant developed severe thrombocytopenia. No bleeding complications were observed, and no infant in either group had such GDM-related complications as polyhydramnios, macrosomia, neonatal hypoglycemia, or respiratory distress syndrome.
Because long-term corticosteroid treatment may promote the development of diabetes in pregnant women, glucose tolerance testing should be done early in the course of pregnancy in steroid-treated women.