Glucose Challenge Test For Pregnant Women
The glucose challenge test measures your body's response to sugar (glucose). The glucose challenge test is done during pregnancy to screen for gestational diabetes — diabetes that develops during pregnancy.
The glucose challenge test is done in two steps. First you drink a sugary solution. One hour later, your blood sugar level is measured. The results of the glucose challenge test indicate whether you might have gestational diabetes.
If the test results are above normal, you'll need to have further testing to determine the diagnosis.
Why it's done
The glucose challenge test is used to screen for gestational diabetes. The test is generally done between weeks 24 and 28 of pregnancy.
However, it can be done as early as your first prenatal visit if you're at high risk of gestational diabetes due to obesity, a personal history of gestational diabetes, a family history of diabetes or other factors. Abnormal test results early in pregnancy might indicate that you have pre-existing type 2 diabetes that wasn't previously recognized, rather than gestational diabetes.
Most women who have gestational diabetes deliver healthy babies. However, without careful management, gestational diabetes can lead to various pregnancy complications, such as preeclampsia or excess fetal growth — which might increase the risk of birth injuries or prompt a C-section delivery.
How you prepare
You can eat and drink normally before the glucose challenge test.
Consult with your doctor about any medications you’re currently taking. Some medications, such as corticosteroids, beta-blockers, diuretics, and antidepressants, can interfere with the results.You’ll need to fast for at least eight hours before the scheduled test.
You may drink water, but avoid other beverages, including coffee and caffeinated tea, as these can interfere with the results.
Avoid going to the bathroom just before the procedure because you may need to provide a urine sample.
Bring something to read or an activity to keep you busy while you wait.
What you can expect
The glucose challenge test is done in two steps. When you arrive at your health care provider's office or lab, you'll drink about 5 ounces (about 148 milliliters) of a syrupy glucose solution that contains 1.8 ounces (50 grams) of sugar.
You'll need to remain in your health care provider's office or lab while you wait for your blood sugar level to be tested. Consider bringing a quiet activity with you.
One hour later, a blood sample will be taken from a vein in your arm. This blood sample will be used to measure your blood sugar level.
After the glucose challenge test, you can return to your usual activities immediately.
Results of the glucose challenge test are given in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L).
A blood sugar level below 140 mg/dL (7.8 mmol/L) is considered normal.A blood sugar level of 140 mg/dL (7.8 mmol/L) or higher might indicate gestational diabetes.
Some clinics or labs use a lower threshold of 130 mg/dL (7.2 mmol/L) when screening for gestational diabetes.
If the results of your glucose challenge test indicate the possibility of gestational diabetes, your health care provider will do another test — typically the glucose tolerance test — to determine the diagnosis.
Risks of a glucose tolerance test
These tests have no serious risks. If you’re being tested for gestational diabetes, this test has no associated serious risks for your or your baby.
Breaking the skin barrier can slightly increase your risk of infection. Watch for signs of infection, such as redness and swelling around the puncture site, and fever. You may also feel faint or dizzy from not eating. It’s a good idea to eat after the test.
Some people find the glucose drinks difficult to tolerate, especially those with higher levels of sugar.