At what gestational age should women be tested for gestational diabetes mellitus (GDM)?

Testing for gestational diabetes mellitus (GDM) is recommended between 24 and 28 weeks of gestation. This timing is critical because gestational diabetes typically develops during the second half of pregnancy when insulin resistance increases due to hormonal changes.

Screening at this point ensures early identification and management of GDM, which can have significant implications for both maternal and fetal health. Untreated GDM can lead to complications such as macrosomia, preeclampsia, and increased risk for cesarean delivery, among others. Identifying GDM in this timeframe allows for timely interventions, dietary modifications, and monitoring that can prevent adverse outcomes.

Testing too early, such as at 20-22 weeks, would be inadequate since GDM is not usually present earlier in pregnancy. Waiting until 30-32 weeks or even later, such as 36-38 weeks, could delay diagnosis and treatment, increasing risks to both the mother and baby. Therefore, the recommended testing window of 24-28 weeks is strategically chosen to maximize the effectiveness of diagnosis and management of gestational diabetes.