Gestational Diabetes Screen (ACOG Recommendations)

Screening test for gestational diabetes

The patient need not be fasting. The one-hour screen requires a 50-gram oral glucose load or 50-gram "Fresh Test" product (https://www.labcorp.com/provider-services/programs/partners-pregnancy) followed by a plasma glucose determination one hour later. (Refer to Additional Information below.) See the online Endocrine Appendix: Glucose Tolerance: Gestational Diabetes Mellitus for further information regarding glucose tolerance testing.

Enzymatic

The American College of Obstetricians and Gynecologists (ACOG) recommends that all pregnant women be screened for gestational diabetes mellitus (GDM)—whether by patient history, clinical risk factors, or with a 50-gram, one-hour loading test at 24 to 28 weeks of gestation to determine blood glucose levels—and suggests relying on the result of the 100-gram, three-hour oral glucose tolerance test for diagnosis (often referred to as a "two-step" method).²

The American Diabetes Association (ADA)³ released standards that vary from the ACOG recommendations. The ADA recommends a simplified "one-step" approach to the screen and diagnosis of gestational diabetes mellitus with a 75-gram, two-hour glucose tolerance test. The LabCorp test according to the ADA recommendations is Gestational Glucose Tolerance Screening and Diagnostics Test (Two-hour, ADA Recommendations) [101000]. A glucose tolerance screen glucose threshold >139 mg/dL after a 50-gram load identifies approximately 80% of women with gestational diabetes mellitus, while the sensitivity is further increased to approximately 90% by a threshold >129 mg/dL. Perform a diagnostic 100-gram oral glucose tolerance test (102004) on a separate day on women who exceed the chosen threshold on 50-gram screening.