Usually between 24-28 weeks of pregnancy, but possibly as early as your first visit if you are high-risk.
The 1-hour glucose tolerance test is usually done between 24-28 weeks of pregnancy. However, you may be asked to do the test as early as your first prenatal visit if you have certain risk factors (such as having GDM before, carrying twins, or if you are obese). If that early test is negative, you’ll need to repeat it again at the usual time.
Reviewed by Jennifer Lincoln, March 2020