Important Tests during pregnancy help check the baby's growth and health, as well as the mother's well-being.
Glucose screening tests check for the signs of gestational diabetes. Gestational diabetes is a common condition during pregnancy that affects up to 10% of pregnant people. It means you have too much glucose, or sugar in your blood.
Gestational diabetes test should be treated immediately as it can cause problems for both you and the fetus. The two types of glucose tests performed during pregnancy are glucose challenge test and glucose tolerance test. Know more details about these screening tests in the following sections.
- What are Glucose Screening Tests During Pregnancy?
- Glucose Challenge Test
- Glucose Tolerance Test
- When to Take Glucose Challenge Test During Pregnancy?
- How to Prepare for a Glucose Screening Test?
- Detailed Procedure of Glucose Challenge Test
- How to Prepare for Glucose Tolerance Test?
- Procedure of the Glucose Tolerance Test During Pregnancy
- Results of Glucose Challenge Test
- What is the difference between Glucose Tolerance Test and Glucose Challenge Test?
- What is the 2 step glucose challenge test?
- What is the normal range of GCT and GTT?
What are Glucose Screening Tests During Pregnancy?
A glucose screening test is a routine test recommended during the 24 weeks of pregnancy. It checks blood glucose (sugar) level in the pregnant woman. Gestational diabetes is a high blood sugar (diabetes) that begins or is identified during pregnancy.
To perform the test, you must drink a liquid containing glucose. Your blood sample will be drawn 1 hour after you drink the glucose solution to test your blood glucose level. If your blood glucose is too high, you must take a glucose tolerance test.
Learn About: Blood Tests During Pregnancy First Trimester
Glucose Challenge Test
The glucose challenge test is a screening test which detects an increased probability of gestational diabetes. It is one of the routine tests during prenatal care. An irregular result means there is an increased chance of gestational diabetes. However, it doesn’t diagnose gestational diabetes. The other names of glucose challenge test are glucose screening, gestational diabetes screening and one-hour glucose challenge test.
Glucose Tolerance Test
This test also diagnoses gestational diabetes. It takes almost 3 hours to give the results and involves drawing your blood multiple times at specific intervals. The test is more involved and requires you to fast. The glucose tolerance test pregnancy is also called as three-hour glucose test.
When to Take Glucose Challenge Test During Pregnancy?
Screening for gestational diabetes occurs around 24 to 28 weeks of pregnancy. Your healthcare provider may perform testing sooner if you:
- Had diabetes in a prior pregnancy.
- Have sugar in your pee during a prenatal visit.
- Have a family history of diabetes.
- Have obesity.
- Have high blood pressure.
- Are older than 35.
- Have a condition like PCOS (polycystic ovary syndrome) or another condition associated with an
- increased risk for diabetes.
How to Prepare for a Glucose Screening Test?
There is no need to prepare for one-hour glucose screening test. Most healthcare providers advise avoiding foods high in sugar for breakfast such as pancakes, juices, or donuts. If you are taking a test later in the day, be aware that eating large quantities of sugar for lunch may affect your results.
Detailed Procedure of Glucose Challenge Test
Here is the complete process of the glucose screening test.
- The lab assistant recommends you to drink a sweetened liquid called glucola just before taking the test.
- After 1 hour of drinking the solution, the blood sample is collected from your vein.
- The blood test measures how the glucose solution is processed by your blood.
- Your are advised to not eat anything from the time you drink glucola until after your blood draw.
A higher-than-normal blood glucose level after 1 hour doesn’t mean you have gestational diabetes. It means your provider will order a second glucose test to diagnose gestational diabetes.
How to Prepare for Glucose Tolerance Test?
It is the second test to diagnose gestational diabetes. This test is similar, but lasts longer and requires more blood draws. Your pregnancy care provider will give you specific eating instructions before your test. The test instructions may include:
- Eating at least 150 grams of carbohydrates per day for 3 days before testing.
- Restricting all food and drink for at least 8 to 12 hours before the test. Drinking a few sips of water the morning of the test is usually OK.
- Scheduling your test for first thing in the morning.
It’s important to note, it’s important to fail your glucose screening but pass a glucose tolerance test.
Procedure of the Glucose Tolerance Test During Pregnancy
Unlike the glucose challenge test, drinking the glucose solution isn’t the first step in a three-hour sugar test for pregnancy. Firstly, a phlebotomist will take your fasting blood glucose level. This is your blood sugar level on an empty stomach.
Then, you will quickly drink a sweetened liquid containing 100 grams of glucose. You will have your blood drawn after one, two and three hours from the time you complete your drink.
You are not permitted to leave while you wait for your next blood draw. Most providers allow you to have sips of water during the testing period. However, you aren’t permitted to eat anything until after your last blood draw.
Results of Glucose Challenge Test
Glucose screening test results are given in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L)
- A blood sugar level below 140 mg/dL is considered as standard.
- A blood sugar level of 140 mg/dL to less than 190 mg/dL signals the need for a three-hour glucose tolerance test to diagnose gestational diabetes.
- A blood sugar level of 190 mg/dL or higher indicates gestational diabetes. Anyone at this level needs to monitor blood sugar at home before breakfast and after meals.
Some clinics or labs use a lower threshold of 130 mg/dL when testing for gestational diabetes. People with gestational diabetes may be able to prevent complications by managing blood sugar levels throughout the rest of the pregnancy.
FAQs on Glucose Screening Test During Pregnancy
1. What is the difference between Glucose Tolerance Test and Glucose Challenge Test?
Glucose challenge test is one hour test that involves drinking sweet solution, and it gives the results quickly. Glucose tolerance test is a three hour test that needs fasting blood sample.
2. What is the 2 step glucose challenge test?
The glucose challenge test is done in two steps. The first step is drinking a sugary drink. After one hour, blood sugar and gestational diabetes are measured.
3. What is the normal range of GCT and GTT?
The normal range of glucose challenge test is 140 mg/dL. The glucose tolerance test range is 95 mg/dL.
Conclusion
We are expecting that enough information is provided regarding glucose challenge test and glucose tolerance test. Both tests are used to check gestational diabetes in pregnant woman. Get to know more about other pregnancy screening tests at our site.