What To Eat Before a Gestational Diabetes Test

Emily Piazza, MD, RDN, CD

So your blood glucose test is coming up and you’re feeling… overwhelmed. Questions like “what happens if I don’t pass”, “what even is gestational diabetes”, and “what can I eat before a gestational diabetes test” are top of mind.

I know this can feel like a really intimidating doctor’s visit, which is why I want to help you feel fully prepared and empowered heading in to your appointment. Read on to learn more about how to prepare for your gestational diabetes test and what a gestational diabetes diagnosis may mean.

What is gestational diabetes

First off- why do pregnant people have to take a glucose test and what does “passing” or “failing” mean? This lab work is commonly completed during pregnancy and is done to screen you for gestational diabetes or confirm that you have it. 

If you’re at average risk of gestational diabetes, you’ll probably be screened during your second trimester (around 24 and 28 weeks). If you are at higher risk your provider may screen you earlier, during the first trimester. High risk factors include things like a gestational diabetes in other pregnancies, a previously large baby, pre-diabetes before pregnancy, and other health conditions, like PCOS.

Gestational diabetes is essentially a “pregnancy diabetes” that can affect the blood sugars of yourself and your baby. While some precautions may need to be taken if you are diagnosed (see below), know that you are not a “failure” if you are diagnosed with gestational diabetes and you can still have a completely healthy pregnancy.

What to eat before a gestational diabetes test

I know you’re probably wondering “what should I not eat before a gestational diabetes test” or maybe you found this blog because you were googling “what to eat before gestational diabetes test”.

While no one necessarily wants to be diagnosed with gestational diabetes, I want to remind you that this test can give your provider (and you) important information about what’s going on in your body, and can equip you to take the best care of yourself and baby during pregnancy.

Could you eat in a certain way to “trick” the test or ensure you pass? Maybe. But again, this isn’t going to be best for you long term and can keep you from getting valuable information about your pregnancy.

This is why it’s important to not alter your diet or try to eat in a “special way” prior to your test. If you’re wondering what to eat before a gestational diabetes test, try to eat as you normally would (unless your provider has you fast beforehand). Eating the way you normally do will give you the best information about how your body is functioning on the inside. Also, try to practice stress reducing techniques as needed. This process can bring up some challenging thoughts and emotions, regardless of the outcome.

Remember- this is just another tool to help you care for yourself and inform your choices during pregnancy. It does not reflect your value or worth.

What to expect at a gestational diabetes test

The most common “test” you will experience is the Glucola drink. In this appointment you will be asked to quickly drink a liquid that is very sweet (think a juice that has a bit too much sugar in it). Some people say they love the drink, others hate it.

One hour after you drink the liquid your blood will be drawn (so bring a book or something to entertain you while you wait!). If your blood-glucose level is high your provider will likely order another test to confirm that you have gestational diabetes.

The 50 gram Glucola drink is a screening (meaning it is not definitive and is used to see who is more at risk for a certain condition). You can schedule it any time of the day, and if you’re wondering what to eat before a gestational diabetes test like this, you can eat and drink normally. If you have an elevated number (<130mg/dL, 135mg/dL or 140mg/dL depending on the institution) they will recommend coming back to do the 3 hour Oral Glucose Tolerance Test (OGTT) with 75 or 100 grams of a glucose drink. 

The only diagnostic test used for gestational diabetes (that can actually be used to diagnose you) is the oral glucose tolerance test (OGTT) with 75 or 100 grams of glucose. With the 75 and 100 gram diagnostic tests you’ll need to be fasting for 8-10 hours before the first blood draw. You won’t be able to eat any food during this 3 hour process, so having a bedtime snack the night before can be helpful. 

After the test, given the fact that you haven’t eaten breakfast and your body just had to process straight sugar and you were told you couldn’t eat food, chances are you’re going to be hungry. Pack a hearty meal or snack or make sure there is a yummy place to get some food afterwards. 

Also, take a moment to assess how you are feeling after the test. Do you want to go into “screw it” mode and go on a carb or sugar binge (this can be especially common if you restricted before the test or went on a low/no carb diet)? Allow your mindset following the test to inform your choices and your need to reach out for help in your relationship with food.

There are alternative methods to the Glucola drink, but the evidence for these tests are limited. If you are hesitant about the Glucola drink, feel free to talk to your provider about your other options.

Remember that you always have the right to refuse any screening or diagnostic test. If you are feeling nervous about taking the test due to possible results or feelings it may evoke, I encourage you to lean on friends, family, and professional support to help you process these feelings.

What to do if you are diagnosed with gestational diabetes

So you completed the test and the results are in: you have gestational diabetes. As a gestational diabetes dietitian here are a few first steps I recommend:

1. Don’t panic! I know this may sound simple but it really is the best first step. Remind yourself that it is still completely possible to have a healthy pregnancy with GD. Thousands of people with gestational diabetes give birth to healthy babies every day.
2. Ditch the restrictive mentality. While you now have new information that can help inform your food and lifestyle choices, remember that a gestational diabetes diagnosis does not mean it’s time to go on a low calorie or low carb diet. Reject the idea that you will just “have to be miserable” and eat plain salads from now on. This mindset can actually lead to the binge-restrict cycle which is harmful to blood sugars. Learn more about ditching the diet mentality and the binge-restrict cycle here.
3. Assess your current relationship with food. A gestational diabetes diagnosis can be hard on your relationship with food, especially if you have struggled in the past. If you have been diagnosed with an eating disorder or have experienced disordered eating habits I highly encourage you to work with an intuitive eating gestational diabetes dietitian during this time. You deserve to have a healthy relationship with food while also managing your blood sugars (and your baby deserves to see what a healthy relationship with food looks like).
4. Learn about how to manage gestational diabetes. I strongly encourage you to seek professional help and guidance during this time. While doctors will be giving you pamphlets, friends and family will be chiming in with their advice, and Google will offer thousands of recommendations, you deserve tailored support that empowers you instead of shames you.

I was diagnosed with gestational diabetes during my second pregnancy and work with pregnant people every day, so I know how overwhelming this time can be. Read more about my gestational diabetes story and journey here. Remember to take it one day at a time and that YOU matter, just as much as the health of your baby. Don’t be afraid to ask for help that will educate, empower, and guide you through this.

I offer weight-inclusive, compassionate care for those with gestational diabetes who are looking to manage their gestational diabetes and have a healthy pregnancy that feels good physically and mentally.

Click here to book a free call to learn more about my services and if they may be covered by insurance. You can also get started with my FREE Trader Joe’s Gestational Diabetes cookbook here.

Emily Piazza, MS, RDN, CD Gestational Diabetes Dietitian & Doula

I’m Emily, an anti-diet registered dietitian, nutrition therapist and doula. I love working with people who want to feel great in their bodies, ditch diet culture, be their own advocate and can listen to and follow their own intuition. You deserve to have an empowering journey through pregnancy, birth and postpartum and I’m here to help.