Glucose Challenge Test (GCT)

The 1‐hour glucose challenge test ( GCT ) is routinely performed in pregnancy to screen for gestational diabetes mellitus.

It involves drinking a glass of concentrated glucose solution (50 g of glucose dissolved in 250 to 300 ml of water). After one hour has passed, a blood sample is taken to determine the blood sugar level.

The glucose challenge test is used to screen for gestational diabetes during pregnancy. If you’re at average risk of gestational diabetes, you’ll likely be screened during your second trimester — between 24 and 28 weeks of pregnancy.