If you're nearing your third trimester of pregnancy, your doctor might have mentioned the pregnancy glucose test. It's typically referred to as the Glucose Screening test or the Glucose tolerance test. This test is offered to you between your 24th and 28th week of pregnancy.
You've heard of it. It's the appointment reminder on your phone that you're probably dreading. You've likely seen an Instagram post or two from the women in your social circle displaying their (typically) orange-colored liquid in their doctor's office as they prepare to test their blood sugar.
This lovely test's purpose is to figure out if you have something called Gestational Diabetes Mellitus (GDM). The Glucose Screening Test is a routine test that every pregnant women is offered in order to screen for GDM in their pregnancy.
The problem is, sometimes the glucose test in pregnancy comes out of the blue with no warning! If you weren't caught up on all of the things that are expected of you during pregnancy, you might be caught off guard when the time comes.
Feeling like you have a pop quiz to take without any preparation is no fun for anyone. I want to make sure you're informed about the pregnancy glucose test and what to expect before you test.
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What you need to know about the pregnancy glucose test
From the time you find out your pregnant to the day you deliver, your pregnancy will involve many different tests. Some are exciting and you may even look forward to them. This one, the pregnancy glucose test, will not be one of those.
Your provider during pregnancy wants to know how your body manages the sugar that you consume. This way, they can understand how your body is processing the foods that you eat while you're trying to grow a human. (It's pretty important). You'll go about finding this out by testing your blood glucose (sugar) level after consuming something high in carbohydrates.
When is the pregnancy glucose screening done?
The glucose screening test in pregnancy usually happens towards the end off the second trimester, between 24 and 28 weeks of pregnancy.
If you are at a high risk for developing GDM, your provider may check your blood glucose levels earlier in pregnancy. Depending on your situation, your provider may request your blood sugar to be checked as soon as your pregnancy is confirmed. If this is the case for you and your initial blood sugars are within normal range, you can still expect to be tested again between 24 and 28 weeks of your pregnancy.
Why the Pregnancy glucose test is performed
The pregnancy glucose tests screen for gestational diabetes by identifying abnormalities in the way your body handles glucose after eating.
Gestational diabetes starts when the body is unable to make all of the insulin it needs during pregnancy. Insulin is required to transport glucose from the blood into your cells. Higher hormone levels in pregnancy in addition to lower insulin levels can result in insulin resistance. Insulin resistance will inadvertently cause cause high levels of glucose to build up in the blood.
Having elevated blood glucose levels during pregnancy raises concerns for you and your baby and should be treated with care. Because GDM can be a serious concern, obstetric providers are vigilant about screening for it to effectively identify and manage the disease.
Gestational Diabetes melitus (GDM)
Gestational Diabetes Mellitus is high blood sugar that is brought on by pregnancy and typically resolves after delivery. According to the American College of Obstetricians and Gynecologists (ACOG) with this condition, a pregnant mother's body passes more sugar to her baby than it needs.
Uncontrolled diabetes during pregnancy can cause your baby to gain more than the recommended weight for a newborn. GDM can even cause problems during labor and even may lead to complications that result in a C-section.
Why is gestational diabetes a concern during pregnancy?
Gestational diabetes mellitus carries risk for baby and for you.
These are the possible complications that may result from your GDM diagnosis:
- Hypertensive disease in pregnancy – GDM can increase your risk of preeclampsia during your pregnancy.
- Large birth weight (Macrosomia) – GDM may increase your baby's risk for being in the 95th percentile or higher in weight.
- Low Blood sugar at birth (hypoglycemia) – After delivery, the blood glucose level can drop very low. This happens because the extra glucose in mother's blood stream trigger's baby's body to make more insulin which can lead to hypoglycemia after birth.
- Cesarean Section – Having a large for gestational age baby can make vaginal delivery challenging or even risky.
- Shoulder dystocia– If vaginal birth is attempted with a macrosomic baby, there is an increased risk that the baby could get stuck in the birth canal and require intervention to get the baby out past the head.
- Type 2 diabetes – Babies born of mothers with gestational diabetes are at a higher risk for developing type 2 diabetes later in life. Also, the mother herself is at a higher risk of developing type 2 diabetes after a pregnancy with gestational diabetes.
Hold on, though! There is good news! Just because you have gestational diabetes during your pregnancy does not mean that you or your baby will have all (or even one) of the complications that you are more at risk for. These things are what you may expect to happen if your gestational diabetes remains untreated or poorly managed.
If you develop gestational diabetes during your pregnancy, sticking to a thoughtful and thorough treatment plan can help you have a healthy and happy pregnancy and protect the health of your baby until birth.
Can You Prevent Gestational Diabetes During Pregnancy?
Many risk factors for developing gestational diabetes cannot be prevented or changed. Risk factors including being 30 years of age or older, having a first-degree relative with diabetes, or being of Hispanic, African American, Native American, South or East Asian, or Pacific Island descent are all part of who you are that might put you at a higher risk of the diagnosis.
On the other hand, there may be a couple of things that you can do to give yourself a better outcome. For one thing, if you can keep your BMI below 25 before you get pregnant, you can begin to reduce your risk. Keeping your body healthy is the first step.
- Related Read: The Insider's Guide To Pregnancy Fitness Goals
How the test is performed
There are a few ways to test for gestational diabetes and each option is just slightly different from the last. We will go over each of the options that include consuming the glucose drink.
1 hour Glucose test in pregnancy
The 1 hour glucose test in pregnancy is called “the glucose screening test”. Of the different pregnancy glucose tests, this is by far the easiest.
For this screening test, you don't need to prepare any specific way prior to your blood draw. You're not required to alter your diet in any way, and you do not have to fast before the test.
You will be asked to drink a beverage called “the glucola drink” which contains approximately 50 grams of glucose. You'll have to drink the entire thing within 5 minutes and then have your blood drawn 1 hour afterwards. This is because glucose levels normally peak within one hour of consuming sugar.
3 Hour Glucose Test in pregnancy
If you fail the 1 hour pregnancy glucose test (the screening test), you will be instructed to come back to do the 3 hour glucose tolerance test.
Unlike the first test, this one requires a bit of preparation. You will have to fast (not eat or drink anything except sips of plain water) for 8 to 14 hours prior to your test.
After your fasting period, you will be instructed to drink another glucose solution. This time, the solution will contain 100 grams of sugar as opposed to 50 grams.
Instead of a one-time blood draw, this time you will have your blood drawn 4 times in a matter of 3 hours.
- the first blood draw is going to be before you drink the solution. This will provide you with your fasting blood sugar result.
- Next, you will drink the 100 gram solution.
- After you drink the drink, you will get your blood drawn every 60 minutes for three hours.
- Your blood sugar levels will be checked to see if they are in range each time your blood is drawn.
One-Step Pregnancy glucose testing
In some special cases, women may be offered one-step testing as opposed to being offered the one-hour glucose screening test with the possibility of needing the three-hour glucose tolerance test.
In this case, you will have to be present for a one-time, 2-hour glucose tolerance test. By the end of this test, you will have your answer to whether or not you have GDM.
This test is only slightly different than the three-hour glucose tolerance test.
- You will have to fast (nothing to eat or drink other than sips of water) for 8 to 14 hours before your test.
- The first blood draw in this test is going to be before you drink the solution. This will provide you with your fasting blood sugar result.
- You will be instructed to drink a solution that contains 75 grams of glucose.
- After you consume the drink, you will have your blood drawn every 60 minutes for two hours.
- Each time your blood is drawn before and during this test, your blood sugar will be checked to see if your levels are out of range at any time.
How to prepare for the Pregnancy Glucose test
It is important to continue eating as you normally would in the days and weeks prior to your test. This is the case regardless of which test is recommended for you. Try not to modify your diet in anticipation for the test.
What you need to be careful of is your medications and herbal supplements that you're taking prior to your test. Make sure you communicate with your provider all of the medications and supplements that you are taking to make sure that none of them will interfere with your test results.
How long do you have to Fast for the glucose test during pregnancy?
If you are taking the one hour test, you will not have to fast at all. You can eat normally prior to the test. I only recommend that you be smart about your choice of food immediately prior. Try low carb foods and non-processed foods for the meal immediately before your test.
If your doctor tells you that you have to fast prior to your test, it might be because you have failed the one hour glucose screening test or you are doing the one-step test. In this case, you will have to fast for 8-14 hours. Fasting over-night while you sleep and scheduling your lab draw for early in the morning is probably your best option.
What to expect from the Pregnancy glucose test
before the glucose test
Although the anticipation of the test might be a little unnerving and the temptation to find out what you can do prior to the test to make it easier is strong, there isn't much you can do prior to the test to make it any better.
If you are doing the one-hour test and do not need to fast, I recommend that you schedule your test for early in the morning. Have a small breakfast and try to avoid consuming a ton of sugar immediately before the test. You are already going to be given 50 grams of sugar, so you don't want to over-do it with the carbs in your breakfast. Two eggs, bacon, and a slice of whole wheat avocado toast would be more appropriate than a plate of pancakes with syrup and a glass of orange juice. Make sense?
If you are doing a test that requires fasting, make sure you get your test scheduled for as early in the morning as possible so that you don't have to starve all day. Fasting while you sleep is a whole lot easier than fasting all day, don't you think?
If you normally workout in the mornings, then you should continue that routine even on the day of the test. Keep your routine as normal as possible so that the results will be accurate compared to your every-day life.
During the glucose test
For each test, no matter which one is recommended for you, you will have to drink a less-than-pleasant drink. Some people say that the drink is horrendous. Other people think that it just takes like flat, very sweet soda.
I have to agree with the group that says it takes like flat soda. It's not as bad as some people make it out to be. It's just not going to be your favorite, either.
You are going to be required to drink the entire drink in five minutes. You won't be able to casually sip on the thing…you're going to have to chug it. Because of that, the drink might make you feel incredibly sick. If you are particularly sensitive to nausea, be prepared for this side effect.
After you drink the solution, you're going to have to sit in the office or lab for the entirety of the test. Whether it's one hour or three hours, you're stuck there. You won't be able to eat or drink anything other than the glucose solution during your test and you probably won't be able to go far, either.
After the glucose Test
After all of the blood draws have been completed, you'll be released to go home and resume your usual activities while you wait for your results.
Depending on the lab you use, you might have to wait a few hours or days before you receive your results. You may even wait longer if your doctor needs to contact you directly to inform you of your results. Luckily, many labs and clinics provide online access to your chart so you can see your results right when they are posted.
If your results fall within normal range, then you don't have gestational diabetes and you can go on with the rest of your pregnancy without being concerned with poking yourself or following a diabetic diet.
On the other hand, if your blood glucose levels are high, your provider may recommend further testing or diagnose you with GDM. You will have this diagnosis for the rest of your pregnancy but fortunately, the diagnosis does not follow you post-delivery.
Results of the Pregnancy Glucose test
Blood sugar levels are measured in mg/dL or mmol/L, which means milligrams per deciliter or millimoles per liter.
Reference values for the 1 hour Oral glucose tolerance test
One hour after drinking the 50 g Glucola drink, a result of anything less than or equal to 140 mg/dL (1.8 mmol/L) will be considered normal. As long as you don't exceed this level you will not be diagnosed with GDM. You're in the clear!
If your blood sugar result an hour after drinking the Glucola is higher than 140 mg/dL (7.8 mmol/L) but less than 190 mg/dL (10.6 mmol/L), you will not be given a diagnosis but you aren't in the clear. In this case, you will be instructed to continue your testing by completing the 3-hour glucose tolerance test on another day.
If, after your one hour glucose test, your blood sugar is greater than 190 mg/dL (10.6 mmol/L), you will be diagnosed with gestational diabetes and will probably avoid the 3 hour glucose test all together.
reference values foor the 3 hour glucose test
After fasting for 8-14 hours, drinking the 100 g Glucola drink, and getting your blood drawn a total of four times, each of your values will be evaluated.
Abnormal blood glucose values for the 3-hour Glucose Tolerance Test:
- Fasting: greater than 95 mg/dL (5.3 mmol/L)
- 1 hour: greater than 180 mg/dL (10.0 mmol/L)
- 2 hour: greater than 155 mg/dL (8.6 mmol/L)
- 3 hour: greater than 140 mg/dL (7.8 mmol/L)
If any ONE of your values are abnormal, you may be asked to test again in four weeks. If two or more of the results are higher than normal, you will be diagnosed with GDM. This diagnosis will be considered for the remainder of your pregnancy.
reference values for the one-step pregnancy glucose test
After fasting for 8-14 hours, drinking the 75 g Glucola drink, and getting your blood drawn a total of three times, each of your values will be evaluated. If any of your values are abnormal, you may be diagnosed with GDM for the remainder of your pregnancy.
Abnormal blood glucose values for the 2-hour Glucose Tolerance Test:
- Fasting: greater than 92 mg/dL (5.1 mmol/L)
- 1 hour: greater than 180 mg/dL (10.0 mmol/L)
- 2 hour: greater than 153 mg/dL (8.5 mmol/L)
What if I fail my pregnancy glucose test?
If your readings come back abnormal and you are then diagnosed with Gestational Diabetes, your provider will have a conversation with you about a treatment plan that you will need to follow for the remainder of your pregnancy.
Taking your diagnosis seriously and treating your diabetes during pregnancy is extremely important in order to protect your health and the life of your baby.
The ACOG recommendations to keep your gestational diabetes under control are as follows:
- Eat regularly to avoid dips and spikes in your blood sugar levels.
- Have three meals and two snacks a day
- Meet with a dietary counselor or nutritionist to discuss changes that you need to be making to your food choices
- Exercise regularly to help control your blood sugar levels
In order to monitor your health for the remainder of your pregnancy, you'll likely be asked to follow these recommendations by ACOG:
- Use a glucose monitor to check your blood sugar levels
- Monitor your blood sugar levels four times a day; fasting in the morning, and an hour after breakfast, lunch, and dinner.
- Keep a log of your blood sugar levels to keep you and your provider on track to how your blood sugars are being controlled.
You may also need to add a couple extra things to your pregnancy to-do list. Depending on your provider's preference, your gestation, and how well your blood sugar levels are controlled, you might be asked to do the following:
- Weekly NSTs in your third trimester
- A growth ultrasound to determine how the baby is growing around 36 weeks
- An insulin regimen to keep your blood sugar levels within range if diet and exercise alone is not working for you.
How To Pass The Glucose tolerance Test in Pregnancy
I'll bet that before the glucose test, your going to be nervous. You might even try to find a way to make sure that you pass the test. Here's a little secret. There is no getting around Gestational Diabetes if you already have it. The best you can do is successfully manage it with diet and exercise for your entire pregnancy.
Trying to figure out how to eat prior to your pregnancy glucose test is pointless and sometimes harmful. Altering your diet in order to attempt to fake the test or encourage a good reading is irresponsible and counter-productive.
Faking a test in order to get a passing score does not take away your possible gestational diabetes. Just because it's not listed in your chart, does not mean that it isn't happening inside of your body.
Ignorance is not bliss. If you don't know that you have gestational diabetes and you go on with the rest of your pregnancy eating as you normally would, you may have poor outcomes that can change your delivery or your child's life forever.
Is the glucose test in pregnancy safe?
risks of the pregnancy glucose test
Experiencing side effects or serious complications from glucose testing are very rare.
Since some women may have to fast for their pregnancy glucose tests, they may experience light headedness, weakness or very low energy. For this reason, it is smart to plan to have someone drive you to and from the test.
In rare cases, the blood collection process may lead to excessive bleeding, fainting, blood collection under the skin, or even infection. Of course, precautions are taken by your phlebotomist to reduce these risks.
Is the glucose test in pregnancy optional?
Of course it's optional. Your health care provider cannot force you to preform any test against your will. You can refuse anything.
That being said, it's an option that you should not overlook or throw out of the window because it doesn't sound like your cup of tea. It is your responsibility to make an informed choice.
What many women don't understand is that these tests are not the only way to know if you have gestational diabetes. You don't have to drink the Glucola drink in order to test your blood for signs of GDM. Ask your doctor about the other options they have available. They exist. You may just have to insist on more information in order to get those options.
What if I'm low risk?
You are at low risk for gestational diabetes if all of the following are true. You:
- Have never had blood sugar level that was out of normal range.
- Are younger than 25 years old
- Have a BMI between 19 and 25
- Are not part of a high-risk ethnic group.
- Have no immediate family members that have diabetes (parent, sibling, or child)
- Have not had any poor outcomes in previous pregnancies
Even if you are considered to be at low-risk for diabetes, it is possible that your body will react to pregnancy in unexpected ways. There aren't necessarily any physical symptoms of gestational diabetes in the mother. Without testing, you may never know how your body is reacting to the sugar you consume during pregnancy or how it is affecting your baby. It is important to test in order to not be ignorant to a life-saving diagnosis.
I hope you feel better!
Now that you're all caught up on what the pregnancy glucose tests are all about, what do you think? Are you feeling better about the idea of the test? Are you wondering what other options you have? I understand. I hope you stay well-informed and educated throughout the remainder of your pregnancy. This is just one of the the things.
Let me know in the comments if you have any questions!
What to read next:
- What to Expect in the Second Trimester of Pregnancy
- Your Second Trimester To-Do List: What to Get Done Between weeks 14 and 27
- 10 Sentimental Ways to Bond with Baby Before They Are Born
- 21 Pregnancy Milestones to Celebrate in Every Stage of Pregnancy
- 13 of the Absolute Best Pregnancy Tips for First Time Moms