on March 31, 2021
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Gestational diabetes is relatively common — but you can have a healthy pregnancy and baby if it's well managed. Catch it early on with a glucose screening.
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In This Article
- What is a glucose screening test?
- Do you have to take a glucose test when you’re pregnant?
- How do I prepare for a glucose test?
- How does a glucose test work?
- What does it mean if a glucose test comes back too high?
- Risks
- What does it mean to have glucose in your urine?
- How to lower your blood glucose levels
Did your practitioner say it’s time to schedule a glucose test? This routine screening checks for gestational diabetes, a condition that affects up to 10 percent of pregnancies, according to the Centers for Disease Control and Prevention (CDC).
So what can you expect when it’s time to take your glucose test — and what happens if the results are higher than normal? Here’s everything you need to know, including the steps you can take to keep your blood sugar where it needs to be.
What is a glucose screening test?
A glucose screening test is a routine pregnancy test that checks for gestational diabetes (GD). The test checks for higher-than-normal levels of glucose (aka sugar) in your blood, which could mean that you have or are at risk of developing GD.
Gestational diabetes can be serious when left unchecked, which is why testing is recommended for all moms-to-be. The good news is that it’s one of the easiest pregnancy complications to manage.
Most pregnant women with GD are able to control their blood sugar through diet and exercise, and if those aren’t enough, medication is an option. In both cases, you’re likely to have a perfectly normal pregnancy and a healthy baby.
For most women, a glucose test is usually done between week 24 and week 28 of pregnancy. Your practitioner might opt to test earlier if you're at higher risk for the disorder, including if you're obese, 35 or older, have a family history of diabetes or had gestational diabetes in a previous pregnancy.
Do you have to take a glucose test when you’re pregnant?
All women should be screened for gestational diabetes, recommends the American College of Obstetricians and Gynecologists (ACOG). So even if you’re not a fan of blood draws or tests, this is one screening you shouldn’t skip.
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Gestational diabetes is one of the most common pregnancy complications. When it goes untreated, it can raise the risk of r a number of problems including:
Macrosomia or a too-large baby, which can make your delivery more difficult or increase the chances of a C-section
Preeclampsia, or the sudden onset of high blood pressure
Jaundice, breathing difficulties or low blood sugar for your baby after she’s born
Higher risk of type 2 diabetes for your baby later in life
Stillbirth
Glucose screenings are an easy and effective way to catch gestational diabetes and get the problem under control, usually with simple lifestyle changes. And that can mean a smoother pregnancy and delivery — and a healthier baby.
How do I prepare for a glucose test?
It depends on the type of test your provider has ordered. If you’re getting the two-step test (sometimes called the one-hour glucose test), you don’t have to do anything special to prepare. It’s fine to eat normally both the night before and the day of the test.
If you’re having the one-step test, you should avoid eating or drinking anything other than water for eight to 14 hours before the test.
If you’re not sure which test your doctor has ordered, just ask. He or she will let you know which screening you’ll undergo and whether there are any special instructions you need to follow to make sure the test results are accurate.
How does a glucose test work?
Wondering how exactly a glucose test is performed? The glucose screening is simple, especially if you have a sweet tooth.
There are two types, and each works a little differently:
Two-step test (also known as the one-hour test): First, you'll drink a very sweet glucose (sugar) drink, which usually tastes like flat orange soda. Then you'll wait for one hour before your blood is drawn and tested for glucose. If your glucose levels are too high, you’ll need to come back for the second step of the test, which involves drinking more of the glucose drink and having your blood tested at multiple intervals.
One-step test (also known as the three-hour test): You’ll have your blood drawn first, then drink the sweet glucose drink. Then you’ll have your blood drawn two more times over the course of two hours.
What does it mean if a glucose test comes back too high?
If the results of your glucose screening show elevated levels of glucose in your blood, it's possible that you might not be producing enough insulin to process the extra glucose in your system.
Your doctor may then order a glucose tolerance test (GTT). For this diagnostic test, you'll be asked to fast (have nothing to eat or drink except water) for eight hours beforehand. Your blood will be drawn, and then you'll drink a higher-concentration glucose mixture. Your blood will be drawn three more times, at one, two and three hours later.
If you’re diagnosed with gestational diabetes, you'll probably work with a registered dietitian to create a special diet plan. You’ll need to limit your intake of high-sugar foods and refined carbohydrates and focus on getting more fruits and vegetables, lean proteins, healthy fats and a moderate amount of complex carbohydrates like whole grains, sweet potatoes and starchy veggies.
You'll also need to monitor your glucose levels yourself several times a day with a home blood sugar meter. This special machine uses a drop of blood from your finger to give you an immediate reading.
If you're not able to control the condition with changes to your diet alone, your doctor may also prescribe a medication to keep your GD in check.
Risks
Glucose tests during pregnancy are safe and don’t come with any major risks or side effects. That said, you might not feel your best after chugging that glucose drink.
Because the drink floods your system with lots of sugar, some women find that they feel a little sick after drinking it — usually nauseous, sweaty or lightheaded. The feeling should ease up after you have some real food, but if it persists or you’re concerned, it never hurts to call your doctor.
What does it mean to have glucose in your urine?
At every prenatal appointment, your practitioner will take a sample of your urine to check, in part, for glucose — a possible sign of gestational diabetes.
If your urine glucose levels are high and you have certain risk factors for developing gestational diabetes, or if your practitioner finds large amounts of glucose at any single testing, you may need to take a glucose screening earlier than usual.
If your urine tests positive for glucose just once, you’re not alone — it happens to roughly half of all women at some point during pregnancy. So don’t jump to diagnose yourself with gestational diabetes. Your doctor may consider it “medically insignificant,” which means it has no effect on your growing baby (and you don’t have gestational diabetes).
More than likely, you simply indulged a high-sugar craving (like a Danish, cupcake, bagel or orange juice) shortly before your urine was tested, which can cause a positive glucose finding in both pregnant and non-pregnant women.
This becomes even more likely from the second trimester of pregnancy on, when your body resists the efforts of the hormone insulin to transport all the glucose you've ingested from your blood into your cells in order to deliver glucose to your developing baby.
Once you've both absorbed the glucose you need, your kidneys dispose of the excess through your urine.
How to lower your blood glucose levels
Even if you have a normal glucose screening and never test positive for glucose in your urine, it’s still important to follow a healthy diet during pregnancy, which can help stabilize your blood sugar levels.
Here are some tips on what to eat to keep blood sugar spikes at bay, plus other smart strategies:
Cut back on “simple” or “refined” carbohydrates.
Muffins, orange juice, sugary cereal and other sweet, refined carbohydrates are the primary culprits behind glucose spikes, because they enter your bloodstream quickly and can result in extra sugar being filtered out through your urine.
Choose healthy carbohydrates instead.
“Complex” or “unrefined” carbohydrates — such as whole grain breads and cereals, whole fresh fruits and even baked potatoes (with the skin on!) — are absorbed more slowly into your bloodstream and are less likely to give you the large sugar jolts that can result in excess glucose filtering into your urine.
In fact, since complex carbohydrates contain more fiber, they actually slow the absorption of sugar into your bloodstream. What’s more, they provide lots of essential nutrients for pregnancy (like folic acid, fiber and iron).
Crush cravings creatively.
If your pregnancy cravings leave you with a hefty appetite for carbs (and let’s be honest, there’s a good chance they will), you can satisfy them while still eating well. Try blending banana slices, milk and ice cubes to make a frothy, banana-split-like shake, enjoy half a fresh grapefruit instead of a large glass of OJ, or make a healthier pizza “slice” by topping a whole wheat English muffin with tomato sauce and low-fat mozzarella cheese.
Be active, every day.
Aim to log 30 minutes of moderate-intensity exercise, like walking or swimming, at least five days a week, ACOG recommends. When you can, try to squeeze in an extra 10- or 15-minute walk after meals. Moving after eating is especially good for blood sugar control.
Gain the right amount of weight.
Gaining too much or too quickly during pregnancy can increase the chances for GD, so talk to your doctor about what you should be seeing on the scale. In general, you should aim to gain 25 to 35 pounds if your pre-pregnancy body mass index (BMI) was in the “normal” range, 15 to 25 pounds if you were overweight before becoming pregnant, and 11 to 20 pounds if you were obese before coming pregnant.
The glucose screening is just one of many tests you’ll undergo during pregnancy. And no matter what the results turn out to be, there are easy steps you can take to keep your blood sugar under control and have the healthiest pregnancy possible.From the What to Expect editorial team and Heidi Murkoff, author of What to Expect When You're Expecting. What to Expect follows strict reporting guidelines and uses only credible sources, such as peer-reviewed studies, academic research institutions and highly respected health organizations. Learn how we keep our content accurate and up-to-date by reading our medical review and editorial policy.