Fasting plasma glucose to avoid a full OGTT in the diagnosis of gestational diabetes

To evaluate the performance of fasting plasma glucose (FPG) in determining the need for a full oral glucose tolerance test (OGTT) to diagnose gestational diabetes (GDM) by the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria.

A multicenter cohort study of 4926 pregnant women 20 years or older consecutively enrolled in prenatal care clinics of the Brazilian National Health Service from 1991 to 1995. All women underwent a single 2 h 75 g OGTT by weeks 24-28 of pregnancy and were followed to detect adverse pregnancy outcomes.

A FPG cut-off value of 80 mg/dl indicated that only 38.7% of all women needed to undergo a complete OGTT, while detecting 96.9% of all GDM cases. When the 85 mg/dl cut-off was used, the corresponding percentages were 18.7% and 92.5%, respectively. The fraction of women labeled with GDM who had adverse pregnancy outcomes was nearly identical when using FPG strategies and universal full testing.

Using a FPG cut-off to diagnose GDM and to determine the need for post-load OGTT measurements is a valid strategy to diagnose GDM by IADPSG criteria. This approach may improve feasibility of applying IADPSG diagnostic criteria by reducing costs and increasing convenience.