What is gestational diabetes screening?

Screening for gestational diabetes is a way to look for high blood sugar during pregnancy. You drink some very sweet liquid. Then you have a blood test to see how your body uses sugar (glucose).

How is gestational diabetes screening done?

Screening for gestational diabetes may be done in a couple of ways.

Two-part screening.

• Part one (glucose challenge test): A blood sample is taken after you drink a liquid that contains sugar (glucose). You don't need to stop eating or drinking before this test. If the test shows that you don't have a lot of sugar in your blood, you don't have gestational diabetes.
• Part two (oral glucose tolerance test, or OGTT): If the first test shows a lot of sugar in your blood, then you may have an OGTT. You can't eat or drink for at least 8 hours before this test. A blood sample is taken, then you drink a sweet liquid. You have more blood tests after 1 to 3 hours. If the OGTT shows that you have a lot of sugar in your blood, you may have gestational diabetes.

One-part screening.

Sometimes doctors use the OGTT on its own. If the test shows that you don't have a lot of sugar in your blood, you don't have gestational diabetes. If you do have a lot of sugar in your blood, you may have the condition.

What are the risks of screening?

Your blood glucose level may drop very low toward the end of the test. If this happens, you may feel weak, hungry, and restless. Tell your doctor if you have these symptoms. The test usually will be stopped.

You may vomit after drinking the sweet liquid. If this happens, you may need to take the test at a later time.

Your doctor may do more glucose tests at other times during your pregnancy.