Pregnant? Here’s Everything You Need To Know About the Glucose Tolerance Test

Photo: Getty Images/Oscar Wong
You’re nearing your third trimester and you’ve been told you have to take a test for diabetes at your next appointment. Maybe you’ve seen the posts on the message boards—the desperate ones that say, “Help! I failed my glucose test!” or “I ate candy today! Will I fail my test?” Now you’re nervous and wondering what exactly this test is and how you can prepare.

The oral glucose tolerance test (OGTT) is typically done around 24 to 28 weeks of pregnancy to test for gestational diabetes, a condition that can occur during pregnancy due to a large shift in hormones. It can happen because pregnancy hormones make your body less efficient at processing the carbohydrates from your diet. As a result, blood glucose levels can be too high.

Experts In This Article

It is recommended that all pregnant people receive the OGTT to detect gestational diabetes. Untreated gestational diabetes can lead to complications during pregnancy—including growing large babies that are hard to deliver, or going into pre-term labor.

While clinically it seems simple—you drink something sugary, then have your blood drawn—many women are underinformed about the test, leading to anxiousness and fear. Most know they will have to take the test, but may be unsure why. “The glucose test was not explained well at all. I just knew I had to drink the stuff and it was to test for gestational diabetes,” says Michelle Hytinen Palmgren, who’s taken the test with each of her three pregnancies. “I didn’t know what I was drinking or how it works, and still don’t know.”

The truth is, it’s nothing to be nervous about. As a certified diabetes care and education specialist, here’s what I want you to know.

What does the oral glucose tolerance test involve?

In a nutshell, you are given a drink that contains 50 to 75 grams of sugar that will raise your blood glucose. Then, an hour later, your blood levels are checked to see how your body responds. If your levels are high during the one-hour test, you will be referred for a three-hour test. During the three-hour test, your levels are first checked after fasting. Then you’ll consume the drink and have blood drawn every hour for three hours afterward.

What does the glucose tolerance test drink taste like?

Let’s talk about the actual drink. Some people tolerate it just fine, comparing it to flat orange soda. On the other hand, some don’t do so well. The large load of glucose alone can make you feel anxious or nauseous. Mandi Brayak, a mother of three, has an aversion to certain drinks. “Having to drink the glucose drink was quite anxiety-inducing for me,” she says. Her doctor’s office made some accommodations for her, such as allowing her to refrigerate the drink to make it more palatable.

Other people may be trying hard to eat a clean and healthy diet for their pregnancies, and do not want to consume the standard orange drink. This was the case for Jody Pontius, whose midwife suggested that she drink fruit juice instead. “I still consumed the same amount of simple sugars but without other added ingredients,” she says. “I much preferred this.”

Don’t think of it as ‘failing’

Another part of the test that causes stress is that it’s often deemed a “pass” or “fail.” As a certified diabetes care and education specialist, I think it’s time we change the way we talk about OGTT results. Failing a test makes it sound as though you are personally responsible for the results, as if you did something wrong. If your lab results come back high, you didn’t fail. It’s just that your body isn’t processing glucose as well as it normally does when you aren’t pregnant. There’s no need to feel ashamed. You just need to take action.

If your lab results come back high, you didn't fail... You just need to take action.

If you are diagnosed with gestational diabetes, you’ll work with your care team to make sure your blood glucose levels are safe for your baby. This usually means you’ll change some of your food choices and meal patterns. It might also be beneficial to prioritize regular movement. And sometimes management also requires medication.

How to prep for the glucose tolerance test

So how do you prepare for the OGTT? Kristin Mallon, CNM, MS, RNC-OB, a certified nurse midwife, says, “We don’t tell women to do anything in preparation for the test because we want the test to reveal accurate results as to how they respond to a glucose load.” Although some pregnant people will avoid sugar and simple carbs in the hours before the test, the purpose is to get an idea of how your body normally reacts, so you’ll want to just keep eating how you normally would so that it’s realistic.

By and large, the OGTT is well-tolerated—there’s no need to fear. But if you are nervous or anxious, Mallon has some suggestions. “Utilize any tricks you normally use to combat anxiety, such as meditation, mindfulness, yoga, going for walks in nature, exercising, talking to a friend, or discussing your concerns with your provider,” she says.

You deserve to be informed, so ask questions. Your provider has the answers. Developing an open relationship with them will make the entire process less stressful.

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