Gestational diabetes: what is the relevance of the glucose challenge test?

To the Editor: The recent letter by McElduff and Hitchman1 has some very practical implications. They were able to show that pregnant women having a glucose challenge test (GCT) in the afternoon were nearly twice as likely to have a positive result as women tested in the morning, so that more women tested in the afternoon were diagnosed with gestational diabetes mellitus (GDM). If the function of the GCT is to aid in the diagnosis of GDM, then either all women should be tested in the afternoon or the glucose "cut-point" for the morning test should be reduced.