When
Sources differ
Sources give different timing:[2][3][1][4][5]
- The US Preventive Services Task Force advises screening at 24 weeks or later.[2]
- NICHD says screening usually happens between 24 and 28 weeks.[3]
- CDC says testing is usually done at 24 to 28 weeks.[1]
- ACOG says glucose screening is usually done between 24 and 28 weeks.[4]
- OWH lists glucose challenge and tolerance tests at weeks 26 to 28.[5]
The USPSTF says there is not enough evidence to weigh screening before 24 weeks.[2] CDC says people at higher risk may be tested earlier.[1] MedlinePlus says people at higher risk may be screened at the first visit.[6]
How it works
ACOG says you drink a sugar mixture, and blood is drawn an hour later.[4]
MedlinePlus says gestational diabetes happens when the body cannot make the extra insulin that pregnancy needs.[6]
After the test
CDC says about half of women who had gestational diabetes later develop type 2 diabetes.[1] ACOG says to be tested 4 to 12 weeks after birth, then every 1 to 3 years if results are normal.[7]
Questions families ask
When is the glucose test done?
ACOG says usually between 24 and 28 weeks.[4] The USPSTF advises screening at 24 weeks or later.[2]
How long does the glucose test take?
ACOG says blood is drawn an hour after you drink a sugar mixture.[4]
Free from UpOnly Learning. Written for families of every faith. No outside ads and no affiliate links. Every fact on this page comes from the sources listed below. How we source and review these pages
Updated 2026-10-24: first published.
Sources
All sources were opened and checked on the date shown.
- Centers for Disease Control and Prevention. Gestational Diabetes. Checked October 24, 2026.
- US Preventive Services Task Force. Gestational Diabetes: Screening. Checked October 24, 2026.
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NIH). What happens during prenatal visits?. Checked October 24, 2026.
- American College of Obstetricians and Gynecologists. Routine Tests During Pregnancy. Checked October 24, 2026.
- Office on Women's Health (HHS). Prenatal care and tests. Checked October 24, 2026.
- MedlinePlus (National Library of Medicine). Diabetes and Pregnancy. Checked October 24, 2026.
- American College of Obstetricians and Gynecologists. Obesity and Pregnancy. Checked October 24, 2026.