The glucose test during pregnancy, which screens for gestational diabetes, is typically done between 24 and 28 weeks of pregnancy. It may be conducted earlier if the woman has a high risk for diabetes or if glucose levels in the urine are found to be high during routine visits. The common approach is a two-step test:
- First, a glucose screening test where the pregnant woman drinks a glucose solution and blood glucose is measured after 1 hour.
- If the result is high, a more detailed 3-hour glucose tolerance test follows, which requires fasting and multiple blood draws.
For some, a one-step test with a 75-gram glucose drink and blood draws before and at intervals after drinking is used, also typically around 24 to 28 weeks. Women at higher risk (such as those who are overweight, older, or have had gestational diabetes before) might be tested earlier in pregnancy. In summary, the standard time for the glucose test is during the second trimester, between weeks 24 and 28 of pregnancy.
