Glucose challenge test (GCT)
Quick answer: A glucose challenge test measures your blood sugar 1 hour after you drink a glucose solution, without needing to fast. It is used in pregnancy, usually between 24 and 28 weeks, to screen for gestational diabetes.
- SampleBlood
- TakesAbout 1 hour
- Before the testYou usually do not need to fast; drink the glucose solution as instructed and stay seated until the sample is taken.
- In fertility careA raised result in pregnancy usually leads to a full glucose tolerance test to confirm or rule out gestational diabetes.
How the test is done
- 1You do not usually need to fast
- 2You drink a measured glucose solution within about 5 minutes
- 3You stay seated and do not eat for 1 hour
- 4A blood sample is taken at 1 hour
What your results can mean
Reading your report
Cut-offs vary between guidelines, so discuss your result with your doctor.
If the result is outside the usual range
A raised result means a higher chance of gestational diabetes and usually leads to a full glucose tolerance test. It does not diagnose gestational diabetes by itself.
Who usually has this test
Pregnant women, usually between 24 and 28 weeks, and earlier in women with risk factors such as PCOS or previous gestational diabetes.
Risks and aftercare
Some women feel slightly nauseous after the drink; eat normally once the sample is taken.
Names and options
Also called: GCT, 50 g glucose test, 1 hour glucose screen
Listed by the hospital as
- GCT (GLUCOSE CHALLENGE TEST), PLASMA
Questions about this test
Do I need to fast for the glucose challenge test in pregnancy?
Usually no. The GCT is designed to be done at any time of day. Follow your doctor's instructions, as some clinics use a different test that does need fasting.
What if I vomit after the glucose drink?
Tell the staff. The test usually needs to be rescheduled, as the result will not be reliable.
Is the glucose challenge test the same as the OGTT?
No. The challenge test is a shorter screening test. If it is raised, a longer OGTT with fasting is usually done to confirm.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
Get directions ↗IVF Pulse fertility care at Tamara Hospital →
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.