You’ve taken the dreaded glucose test, got your results back, and you FAILED. Now, you have to go back and take the three-hour test. How can you make sure to pass the three-hour glucose test while pregnant?
Unfortunately, there’s no real easy way to make sure that you pass the pregnancy glucose test. And to be honest, you don’t want to do anything to potentially alter the results!
You want the results of your test to be accurate for you and your baby.
However, there are some steps that you can take to lower your risk of gestational diabetes and help you have a healthier pregnancy. This, in turn, will increase your chances of passing the glucose test while pregnant.
DISCLAIMER: The information on the site is for informational and educational purposes only. Nothing on the site should be considered medical advice. Always consult your own or your child’s health care provider before acting on any information or recommendations. You can read my full Disclaimer Policy here.
First, let’s talk about what actually happens during the pregnancy glucose test and what it means when you ‘fail’ the one-hour test.
What does it mean when you “fail” the one-hour glucose test?
In the United States, the standard way to diagnose gestational diabetes takes two steps.
The first step involves giving all pregnant women a glucose test around 24 weeks. Also called the one-hour oral glucose challenge, this is a screening test to identify women at increased risk of having gestational diabetes.
During the one-hour test, you’ll be asked to drink 50 grams of concentrated glucose (typically in the form of a very sugary drink). You’ll then get blood drawn an hour later to check your blood sugar levels.
Different OB/GYN practices may use different criteria for what is considered “passing” the one-hour glucose test.
Generally, the normal blood sugar range in pregnancy after the glucose challenge test is less than 130 mg/dL.
If your blood glucose level is greater than 130 mg/dL, you will probably need to do the three-hour glucose tolerance test. However, some providers will only recommend the three-hour test if your blood glucose is greater than 135 or greater than 140 after one hour.
In general, if your blood sugar is less than 130mg/dL one hour after drinking 50 grams of concentrated sugar, you’ll pass the test.
If your blood sugar measures between 130-140mg/dL depending on which criteria your doctor uses, you might have to take the 3-hour test. If your blood sugar is over 140, you will most likely have to take the longer glucose test.
Find out more about taking the glucose tolerance test during pregnancy and how gestational diabetes is diagnosed.
What causes a pregnant woman’s blood sugar level to be high?
Sugar, or glucose, is the body’s main source of energy. Glucose from the food we eat passes from the intestines into the bloodstream. In order to be used as energy, glucose needs to move from the bloodstream into the body’s cells. It does this with the help of insulin. Insulin acts like a key to unlock the cells and move glucose into the cell, where it can be used as energy.
When someone has diabetes, there is not enough insulin in the body or the cells aren’t responding to the insulin the way they should.
During pregnancy, the placenta secretes hormones that can cause the body to be resistant to insulin. Most women will produce more insulin to compensate.
Some women, however, are unable to make enough extra insulin. Glucose can’t move from the bloodstream into the cells, so it builds up in the blood, causing high blood sugar levels, which leads to gestational diabetes.
Are you at risk for gestational diabetes?
According to the American Diabetes Association, gestational diabetes mellitus (GDM) affects almost 10% of pregnancies in the United States.
Pregnant women are at an increased risk of developing gestational diabetes due to the following characteristics (source):
- Previous diagnosis of GDM
- Hispanic, Black, Native American, South or East Asian, Pacific Islander
- Family history of diabetes
- Pre-pregnancy BMI greater than 30
- Age greater than 25
- Previous birth of a baby over 9 lbs
- A medical condition associated with the development of diabetes (like polycystic ovary syndrome)
- Pregnant with multiples
Just because you have one or more risk factors does NOT mean you will develop gestational diabetes. However, you are at a higher risk and it’s even more important to screen for GDM with the one-hour test, followed by the three-hour test if necessary.
What happens during the 3-hour glucose test?
Before taking the three-hour glucose tolerance test, you will need to fast overnight.
You should have nothing to eat or drink for at least eight hours (although your OB/GYN office will probably give you more specific instructions).
Water is definitely okay to drink, however!
When you arrive at the lab or testing site, you’ll have blood drawn first to get a fasting glucose level. Then, you will consume a 100-gram oral glucose drink.
Your blood will be drawn one hour after you finish the drink, two hours later, and three hours later. (Yes, they’ll be checking your blood glucose levels FOUR times. Ouch).
The most commonly used criteria for determining if you “pass” the three-hour glucose test is listed below. Typically, you will “fail” if two or more of these values are elevated. However, some doctors may diagnose you with GDM even if you just have just one elevated number.
- Fasting: less than 95 mg/dL
- 1 hour after: less than 180 mg/dL
- 2 hours after: less than 155 mg/dL
- 3 hours after: less than 140 mg/dL
Why is the Glucose Tolerance Test Important for pregnant women (and why you shouldn’t “cheat” the test!)
Gestational diabetes can cause complications for both mom and baby. However, it can be successfully managed (usually WITHOUT medication) when it is identified early.
It’s important to make sure the results of your 3 hour glucose tolerance test are accurate in order to correctly diagnose gestational diabetes so it can be treated. This will help prevent any complications for you and your baby.
Some of the complications seen with gestational diabetes are listed below.
GDM Complications For mom:
High blood pressure
Polyhydramnios (high amniotic fluid levels)
Need for cesarean section delivery
This could happen for many reasons, including the size of the baby or complications during labor
GDM Complications For baby:
Infant that is large for gestational age (weight above the 90th percentile) and macrosomia (birth weight greater than 4500 grams or about 9 lbs)
Glucose crosses the placenta so when too much glucose is in your bloodstream, it can pass through the placenta, giving the baby high blood sugar levels. Since the baby doesn’t NEED the extra glucose, it’s stored as fat. This can which can lead to larger sized babies.
If extra glucose crosses the placenta causing higher sugar levels for the baby, their pancreas will make extra insulin to get rid of the blood glucose. When the baby is born, they are no longer receiving extra glucose from the mom so they don’t need the extra insulin anymore. This can lead to LOW blood sugar levels at birth from too much insulin. (source)
Respiratory distress syndrome
Research has shown a delay in the lung development of babies born to women with uncontrolled gestational diabetes. Although most infants’ lungs are mature by 37 weeks, gestational diabetes babies’ lungs may not mature until after 38 weeks. As many GDM babies are born early, there is a higher risk for respiratory distress after delivery.
Women diagnosed with gestational diabetes are also at a higher risk for developing type 2 diabetes in the future. Therefore, it’s important to know if you do have GDM so you can receive proper testing and follow-up care postpartum.
How can you lower your risk for gestational diabetes?
Most studies evaluating the effectiveness of interventions in preventing gestational diabetes were started early in pregnancy, during the first or second trimesters.
However, it is never too late to start implementing changes that can lead to a healthier lifestyle and reduce your risk of developing diabetes in the future.
Eating well and exercising are known to prevent type 2 diabetes and may be effective for preventing GDM. There is also evidence connecting GDM to sleep and the mental health status of pregnant women.
The following are evidenced based ways to lower your risk of gestational diabetes.
1. Get 150 Minutes of Physical Activity Each Week
Several studies have shown a relationship between physical activity before or during pregnancy and a lower risk for developing gestational diabetes.
The American College of Obstetricians and Gynecologists recommend pregnant women get 150 minutes of moderate-intensity aerobic exercise each week. This can be split up in many different ways depending on what works best for your schedule.
Walking and swimming can be great activities for pregnant women. Prenatal yoga (see #4) and pilates are also great options. However, you should talk to your doctor first about what kind of exercise is safe for you while pregnant.
If you haven’t been exercising regularly already, start out slowly and gradually increase your activity. Even just five minutes a day can be beneficial.
You can find more great tips on finding time to exercise here.
2. Eat a Balanced, Healthy Diet
You don’t want restrictive dieting when you’re pregnant but you do want to eat a lot of nutritious foods with fiber, vitamins, and minerals.
An easy place to start is by following the Plate Method. For any given meal, fill half your plate with vegetables. Then, use ¼ of the plate for your protein and the last quarter for your starch or grains. I find this to be an easy way to plan meals if you get annoyed by measuring out portions or calorie counting.
A study of pregnant women in Spain, found a Mediterranean diet associated with decreased rates of gestational diabetes.
Researchers instructed the women in the intervention group to follow a Mediterranean diet with at least 40 mL of extra virgin olive oil and a handful of pistachios each day.
The diet involved eating:
- At least 2 servings of vegetables per day
- At least 3 servings of fruit per day
- 3 servings of low fat dairy products per day
- Whole grains
- 2-3 servings of legumes per week
- moderate to high amounts of fish
The women also limited red and processed meat and avoided refined grains, processed baked goods, soda, juice, and fast food.
The Mediterranean diet has been shown to prevent type 2 diabetes and heart disease. So, it makes sense that limiting processed foods and added sugar and focusing on getting enough lean protein, fruits and vegetables, and healthy fats are ways to help decrease your risk of GDM.
3. Get 7 to 9 Hours of Sleep Each Night
We all know sleep is good for us, but can the right amount of sleep help prevent gestational diabetes?
A few studies have found a correlation between poor quality sleep and gestational diabetes. Surprisingly, this study also found that women with poor sleep and longer duration of sleep had the highest risk of GDM (compared to women with good sleep and 7 to 8.5 hours of sleep per night).
Another study associated poor sleep quality AND getting less than six hours of sleep per night with an increased risk of GDM.
Getting too little sleep and getting too much sleep both possibly lead to an increased risk of gestational diabetes so aiming for about 7 to 9 hours each night might help prevent GDM.
4. Participate in Prenatal Yoga
A few studies have shown a positive effect of yoga on lowering blood glucose levels and preventing gestational diabetes.
One study involved women already diagnosed with gestational diabetes and concluded that yoga and pranayama (breath control) decreased blood glucose levels to help better control diabetes.
Another study separated high risk pregnant women into a yoga group and a control group. The yoga group participated in one-hour yoga sessions, three times a week, from 12 to 28 weeks of pregnancy. The study found statistically fewer cases of gestational diabetes (along with other complications such as preeclampsia and IUGR) in the yoga group.
Because of the small sample size of women in this study, the researchers concluded that more studies need to confirm their findings. However, prenatal yoga could be a promising intervention for preventing gestational diabetes.
5. Take Probiotic Supplements
Science suggests that probiotics could potentially help prevent gestational diabetes by altering the gut microbiome. Much of the current research is mixed on whether probiotics effectively reduce gestational diabetes cases.
A study published in the British Journal of Nutrition showed improved blood glucose control in pregnant women who started taking probiotics early in pregnancy, suggesting that probiotics may reduce the risk of gestational diabetes.
Studies have also shown better blood glucose control in patients diagnosed with GDM who took probiotics. Women in one study who took probiotic supplements containing Bifidobacterium and Lactobacillus for four weeks had lower fasting glucose and increased insulin sensitivity than those in a control group who received a placebo.
More research is needed but probiotics are potentially beneficial in reducing gestational diabetes risk.
What happens if you fail the 3-hour glucose test?
If you fail the glucose test and are diagnosed with gestational diabetes, the main thing you need to know is that you didn’t really DO ANYTHING to cause it. Although we talked about ways that can potentially help prevent GDM, it is basically an intolerance to glucose that is caused by changes in your body during pregnancy.
So, don’t feel guilty or think that you did something wrong or didn’t do something you should have been doing.
If you are told you have gestational diabetes, your doctor will work with you to manage your blood sugars and monitor you and your baby closely throughout your pregnancy for any complications.
After you give birth, your body should go back to using insulin appropriately and blood sugar levels should normalize.
However, it’s important to get proper follow-up care since women with GDM are at a higher risk for developing type 2 diabetes.
You should have another glucose tolerance test 4-12 weeks postpartum. If that test is within the normal range, the ADA recommends diabetes testing (either the oral glucose test or a blood test) every 1-3 years.
Final Thoughts on How to Pass the Glucose Test During Pregnancy
Unfortunately, there is no secret, magic way to guarantee that you’ll pass the three hour oral glucose tolerance test during pregnancy. More importantly, you want the results to be as accurate as possible so you can make sure you and your baby have a healthy pregnancy.
There are, however, a number of lifestyle modifications you can start implementing to reduce your risk for gestational diabetes. These are especially effective if you have a history of gestational diabetes and want to minimize your risk of GDM for future pregnancies or you are in your first or second trimester and at a high risk for developing GDM.
Most women who are diagnosed with gestational diabetes are able to control their blood sugar through diet modifications. Some will have to go on oral medications or insulin but as long as you are managing your diabetes and being followed closely but your OB and any recommended specialists, the risk of serious complications for you and your baby is low.