Learning About Glucose Testing During Pregnancy

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A glucose test measures the body's ability to use a type of sugar, called glucose. Glucose is the body's main source of energy. This test is used to check pregnant women for gestational diabetes. Gestational diabetes is a form of diabetes that develops during pregnancy and then usually goes away after the baby is born. When you have this condition, the insulin in your body is not able to keep your blood sugar in a normal range. If you do not control your blood sugar, your baby can grow too big and may have problems after birth.

How are glucose tests done?

There are different ways to test for gestational diabetes.

One method is done in two steps.

  1. You do not need to stop eating or drinking before the first step. In this step, you drink a liquid that contains 50 grams of sugar (glucose). Your blood sample is taken 1 hour later. If you don't have a lot of sugar in your blood, you do not have gestational diabetes.
  2. If you do have a lot of sugar in your blood, you are asked to do the second step, the oral glucose tolerance test (OGTT). With the OGTT, you cannot eat or drink for at least 8 hours before the test. Then a blood sample is taken when you arrive for the test. This is your fasting blood glucose value. It provides a baseline for comparing other glucose values. You drink a liquid that contains 75 or 100 grams of sugar (glucose). Your blood sample is taken at timed intervals of 1, 2, and sometimes 3 hours later to see how much sugar is in your blood. If 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 do have gestational diabetes.

A different method is done in one step. It is another version of the OGTT. You cannot eat or drink for at least 8 hours before the test. You drink a liquid that contains 75 grams of sugar (glucose). Your blood sample is taken before the test is started and at timed intervals of 1 and 2 hours later to see how much sugar is in your blood. If you don't have a lot of sugar in your blood, you do not have gestational diabetes. If you do have a lot of sugar in your blood, you do have gestational diabetes.

What else should you know about the test?

Your blood glucose level may drop very low toward the end of the glucose 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, the test may need to be repeated at a later time.

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

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse call line if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Where can you learn more?

Go to https://www.healthwise.net/patientEd

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