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Your Pregnancy and What You Need to Know About Glucose Tests

By Kelcey Kintner

If you’re pregnant, then sometime between 24 and 28 week mark, your doctor will have you come in for a Glucose Challenge Test (GCT).

This is a test to screen whether you might have gestational diabetes, a high blood sugar condition that starts or is diagnosed during pregnancy and will need to be treated.

As far as tests go, this is a whole lot easier than your calculus midterm exam in high school.  You basically drink something that tastes like grossly sweet soda (which is much better cold) and an hour later, you’ll have your blood drawn. Some doctors will give you the liquid to take at home and others will require you to drink it in the office.

Your doctor just wants to make sure you are processing sugar properly.  A high level in your blood may indicate that your body is not.

Now I had no problem with this test during my first and second pregnancies so when it came to my third, I declared myself a glucose champion (I’m sure the trophy is around here somewhere) and I wasn’t concerned at all. Which is why I thought nothing of consuming a gigantic sugary scone before my Glucose Challenge Test.

Do not do this. This is a very bad idea because I failed the test.  On the upside, I did get a B in calculus.

If like me, you fail your Glucose Challenge Test, don’t panic. It doesn’t necessarily mean you have gestational diabetes (remember, it’s just a screening test), but you do now have to take a 3 hour Glucose Tolerance Test (GTT). If you already have children at home, think of it as a 3 hour getaway to surf Facebook and Twitter without interruption. And this getaway comes with a refreshing cocktail! Okay, the drink stinks but at least you’re getting a little alone time.

With the Glucose Tolerance Test (GTT), you will have to fast beforehand and that super sweet drink (extra-concentrated) can potentially make you quite queasy. In fact, it made me very nauseous. I had my own personal mantra of, “Don’t throw-up. Don’t throw-up. Focus on Twitter. Focus on Facebook. Please don’t throw-up” because I had no interest in repeating the experience. Every hour, your blood will be drawn so they can monitor how you are processing sugar over a span of time.

It’s important to know that if you are diagnosed with gestational diabetes (3 to 10% of all pregnancies), you can still go on to have a healthy pregnancy and the condition will likely go away after you give birth. But while pregnant, you will need to make changes to your diet, add daily exercise and possibly take medication to keep your blood sugar levels under control. You will also have to monitor your glucose levels from home. Yes, it sounds like a lot but it’s all vital for the health of you and your baby.

I’m currently pregnant (4th time around) and next week, I’m headed to my doctor’s office for my initial Glucose Challenge Test. I’m definitely skipping the scone and my doctor recommend that I cut back on sugar and carbohydrates 72 hours before the screening test. I think that man is severely underestimating my addiction to Whoppers and Junior Mints but I’m going to do my very best. Fingers crossed for me and all you other pregnant ladies out there.

Note: Did your doctor order a 2-hour Oral Glucose Tolerance Test? It’s very possible. In 2011, the American Diabetes Association adopted guidelines by the International Association of Diabetes and Pregnancy Study Group and started recommending the 2-hour test as a replacement for the Glucose Challenge Test and 3-hour Glucose Tolerance Test.  If you fail the 2 hour test, you are simply diagnosed with gestational diabetes and treated accordingly. No need for a second test.

But for now the American College of Obstetrics has stayed with their current guidelines of a 1-hour screen test (GCT), followed by the 3 hour test (GTT) to confirm/ deny gestational diabetes, believing it protects maternal and newborn health, while keeping health care costs down.

If you have any questions about these different glucose tests, don’t hesitate to talk to your OBGYN.

Published February 22, 2013. Last updated March 27, 2018.
Kelcey Kintner
About the Author

Kelcey Kintner

Kelcey Kintner, an award winning journalist and freelance writer, is a fashion critic for US Weekly, created the humor blog 

Kelcey Kintner, an award winning journalist and freelance writer, is a fashion critic for US Weekly, created the humor blog The Mama Bird Diaries and writes for the Huffington Post. You can follow her @mamabirddiaries or on Facebook. She’s still trying to fit 5 kids on a Vespa. 

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  • Rose

    February 22, 2013 at 9:01 am

    My midwife did prescribe the 2 hour test, and also following a low-carb/low-sugar diet for the 72 hours before.  They said they prefer it because it seems to get more women to pass (including the borderline ones).  I admit, I was not great about the diet (I tried, I tried), but passed with flying colors.  But not without also feeling kind of queasy throughout.  Blech.

  • Myriam

    February 22, 2013 at 9:06 am

    I am a Type 1 diabetic, and I would like to clarify a statement in this article. If you are not diabetic, your pancreas will produce exactly the right amount of insulin to balance out your sugar/carb intake nad your glucose level will not rise above a certain level. So whether you had a scone or not, if you’re not insulin resistant or deficient(two causes of diabetes), your glucose level will be normal. However, it is necommended to cut down on the extra sugar before the test to help your doctor figure out how severe the diabetes might be. The “juice” they give you contains a cerain amount of sugar, and your glucose level after te test will help your doctor determine to what extent nutrition or medication will manage your condition. The main complication for babies of diabetic mom (especially gestional) is to be born too big, increasing risk during delivery. Also, the baby is at risk of hypoglycemia after birth, and will have to be monitored (and pricked) for up 3 days post-delivery. Hope this helps!

    • Myriam

      February 22, 2013 at 9:18 am

      sorry for the typos, I am writing this on a small screen…

      • Kelcey


        February 24, 2013 at 9:47 am

        Great info Miriam. Although my doctor definitely thought the scone played a part in me failing the first glucose test.

        • Myriam

          February 25, 2013 at 9:26 am

          The first glucose test in not really precise and can indeed be “influenced” by too many sweets!

          I would like to add that diabetes, although a hard diagnosis, can be well managed. It is a condition that forces you to be healthy (food, sleep, stress, exercice), and a good reminder that moderation is key in everything, pregnant or not, diabectic or not!

    • Isabel


      February 22, 2013 at 9:31 am

      Thanks, Myriam. We love our smart readers.

    • Sora

      March 2, 2016 at 1:09 am

      “if you’re not insulin resistant or deficient(two causes of diabetes), your glucose level will be normal.”

      So, the thing is, pregnancy — in and of itself — causes insulin resistance. All pregnant women are more insulin resistant than they were before pregnancy.

      A quote from a relevant article: “Human pregnancy is characterized by a series of metabolic changes that promote adipose tissue accretion in early gestation, followed by insulin resistance and facilitated lipolysis in late pregnancy. In early pregnancy, insulin secretion increases, while insulin sensitivity is unchanged, decreased, or may even increase (1,2). However, in late gestation, maternal adipose tissue depots decline, while postprandial free fatty acid (FFA) levels increase and insulin-mediated glucose disposal worsens by 40–60% compared with prepregnancy (2). The ability of insulin to suppress whole-body lipolysis is also reduced during late pregnancy (3), and this is further reduced in GDM subjects (4)”

      Basically, hormones from the placenta help block the action of the insulin in the mother’s body.

  • Nicole

    February 22, 2013 at 9:46 am

    That’s interesting that there is a 2-hour glucose test now. When I was pregnant with my daughter (she’s a little over three now), I ended up having gestational diabetes. I barely failed the screening test (by, I think, 2 mg/dL). In fact, my doctor was more conservative with the numbers, in that her cutoff point for normal blood sugar levels was 5 mg/dL less than what some other doctors used. Had I seen another doctor, I might never have been diagnosed. When I did the three hour test, again, I barely failed, but I failed nonetheless. When I started monitoring my blood sugar levels at home, it became clear that my body wasn’t processing sugar like it should be. I am sure the diet and exercise had an impact on my pregnancy (a good impact). My daughter was 8 lbs 6 oz when she was born. She was big enough without adding whatever weight she might have gained had I never been diagnosed. I can’t help but wonder how I would have done with the two hour test. 

  • Ally

    February 22, 2013 at 9:57 am

    I have never been able to successfully take this test. I’m also pregnant with #4 (yea!) and I’m guessing it will go like the other three and I’ll throw up around the clock all nine months. I tried the test at least twice with the other pregnancies and was never able to keep it down. I had no symptoms of diabetes so my doctor just let it go. 

  • Angel

    February 22, 2013 at 10:03 am

    I had to do botht he 1 hour and 3 hour glucose screens with my son 4 1/2 years ago. I was borderline on the 1 hour so I had to do the 3 hour. I of the 3 blood draws one draw at 2 hours was 2 over. so I was declared to have Gestational diabetes. I was able to control it with out medication by diet alone. I am now pregnant and have just completed my 1 hour screening. It came back elevated but not extremely high so my Dr. is classifing me as gestational diabetic again since I was in my previous pregnancy. Right now I am controling it with just diet again and hoping to make it the 12 weeks I have left in this pregnancy without medications.

  • Michele

    February 22, 2013 at 2:07 pm

    I recommend NOT doing a prenatal checkup right after drinking the glucose. I did and ended up having to spend the whole day getting a non-stress test because my baby’s heart rate was so high. (And she was just fine.)

    • Myriam

      February 22, 2013 at 2:40 pm

      They do recommend drinking a glass of orange juice to “wake your baby up” if you’re worried about them not moving!!! That’ probably why!

  • IrishCream

    February 23, 2013 at 10:14 am

    It’s good to remember that gestational diabetes isn’t a result of eating a few too many sweets before the test. It’s a complex condition involving the interplay of your endocrine system and all those fun pregnancy hormones. Being on the heavier side pre-pregnancy can make you more susceptible, but so can having a family history of diabetes, especially if your own mom’s blood sugar levels were high while she was pregnant with you! I had GDM with both my pregnancies, and having to be strict with my diet and go for extra check-ups was a drag for sure, but of my girls were born perfectly healthy, with no weight or sugar issues. And the silver lining of that strict diet for me…no weight gain beyond what my body needed for a healthy baby, so postpartum weight loss was quick and painless.

    • Kelcey


      February 24, 2013 at 9:56 am

      Thank you so much for sharing your story. It’s really important that people know gestational diabetes can be managed. I hope I didn’t imply that you get gestational diabetes from eating too many sweets. Only that my doctor thought it skewed the results, forcing me to take the 2nd test which I passed with no problem.

  • Autumn

    February 23, 2013 at 11:14 pm

    When I did the test, I was able to chug the stuff (which would have been great with some club soda, lime and vodka. . .my clinic had the orange variety) and then wobble to a follow up ultrasound.  The kiddo was wiggly!  

    I “Passed” by one point.  If we have another, not having the blackberry oatmeal before.  

  • Mona

    February 25, 2013 at 2:38 am

    Good information- I just wanted to add that maternal age can affect GD as well. My first pregnancy (at 34- just squeaking in under the “advanced” category), I passed this test with flying colors (my OB’s words, lol). But my second pregnancy (at 38), I failed both the initial screening and the follow up / three hour test. I’d never had blood sugar issues, so I was quite surprised and a bit distressed about it. But off to the endocrinologist, four X / day monitoring, low sugar / high protein diet I went. And it was all fine. The endocrinologist thought my gestational diabetes was most likely due to maternal age, it was well controlled through diet alone, baby was great and fine, and it went away immediately after he was born. As a plus- the controlled diet really hel

  • Mona

    February 25, 2013 at 2:48 am

    (sorry, premature publish)
    Anyhow, the diet really helped minimize weight gain those last few months and taught me a thing or two about eating better. So, a diagnosis, while a bit unnerving, can work out just fine. I do still test my blood sugar on occasion per doctor’s orders, but have not had any further issues (baby is now 16months and also doing great).

  • Leah

    February 25, 2013 at 10:13 am

    My doctor forgot to mention that they’d be checking for antibodies because of my Rh-negativeness when they did the glucose blood screen. This meant hanging around the doctor’s office for three hours instead of one, and as I had post-appointment plans, my blood pressure became elevated, causing concern about preeclampsia. THE MORAL: If you’re RH negative, realize this may be a longer appointment.

    • Rana

      May 3, 2013 at 12:30 am

      That’s really good to know. I knew about the importance of Rhogam, both at 28 weeks and if there’s any signficant bleeding, but hadn’t heard about the antibody check during the glucose test.

  • leslie

    February 27, 2013 at 11:40 am

    My OB’s office requires the 2-hour test for everyone now (they were still doing the 1-hour when I was pregnant with DD in 2010). Talk about a whole different experience. With the 1-hr, I didn’t have to fast, and I was able to drink the orange stuff at home before going in to have my blood drawn once. Easy Peezy. This time I had to fast from midnight the night before, drink the orange stuff on a very empty stomach at the OB’s office, sit around for an hour, have my blood drawn, and then sit around for another hour and have my blood drawn again. I was so hungry (and had such a horrible sugar headache) the whole time. It was torture! Thankfully I passed. I don’t know how ladies do the 3-hour!! Ugh.

  • allisonjayne

    February 27, 2013 at 2:42 pm

    I think I’m the only pregnant lady who actually liked the orange drink. What can I say, I love orange pop and I tend to abstain from pop in general – and didn’t drink any while pregnant – so it was like a treat! Ok I’m a weirdo.

    I took the
    3 hour test to start because my sister had GD with all of her pregnancies, so I decided I’d rather start with the 3 hour test rather than have to do 2. Passed with no problem. I actually didn’t mind having to wait the 3 hours…like you said, it was like a getaway…work couldn’t bother me, I just had some midday alone time to read and not feel guilty that I wasn’t doing something more productive.

    • Isabel


      February 27, 2013 at 5:13 pm

      i liked the orange drink, too!

  • landry

    March 4, 2013 at 2:00 pm

    drink it with a straw. 
    Its much less gross going down since it doesn’t go over your tongue. A friend suggested it to me and the nurse was mightily impressed with my ingenuity. (I fess’d up and told her that it was recommended by a friend) 

  • Mary

    March 20, 2013 at 1:34 pm

    I know I’m late to the party, but, here’s my experience with the 1 hour glucose test.

    My doctor said to eat normal, but nothing sugary that day, since my test would be in the afternoon.  My Dr’s office also does email notification of new electronic medical records when lab results are in.  3 days after I got an email, there were unofficial results that I passed.  Fabulous. More than 2 weeks after that a nurse called me and said, your Glucose results are in, and you need to go immediately into diabetinc counseling your results were so crazy high.  -I’m sorry, I already had my results you must be talking about someone else. – We confirmed it was me, I went back to my electronic medical records, and what I had seen was gone.  (but I know I didn’t just dream it, because I texted hubby when I saw the results!)… So why did it take so long to get me this bad news?  I thought bad news they tended to relay right away. Why did the results change?  And why aren’t you sending me for the 3 hour test? – Well you’re results are SO high, that it’s against protocol to do the 3 hour test, and the results DIDN’T change, and I don’t know why it took so long. – Listen sister, I dont care about your protocol, I am NOT diabetic, I have NO other symptoms, and these results could EASILY be skewed because of what I ate that day, string cheese, Peanut Butter and Jelly, whatever!  Give me the #@!* 3 hour test! – So you are refusing counseling? – I am until the 3 hour test results are in! – 

    So, after great finangling and stress I was able to take the 3 hour test a few days later, and guess what, EVERY SINGLE blood draw (and there’s 4 of them!) came back as in a good range.  

    So, after I proved my non-diabetic-ness, they claimed they couldn’t remove the first test results from my record.  So every time I had an appointment after that, the first thing the nurse, and then the doctor would say is “oh, it Looks like you have GD.”  LIKE HELL I DO!! READ ALL THE RECORDS BEFORE YOU TALK TO ME NINCOMPOOP!!!  

    Maybe I was a bit hormonal as a pregnant lady….

    Bottom line:  Nurses and Labs screw up.  What you eat affects it.  GO WITH YOUR GUT.  If my 3 hour test had come back positive, I would have gladly started the counseling, but not sending me for the next test was wrong of them.

  • ashley michelle p

    April 25, 2014 at 11:15 pm

    What is in the glucose drink? does anybody know

  • Stephanie

    May 20, 2015 at 10:20 am

    I had a lot of difficulty with the standard test the first time around – failed the 1-hour and nearly failed the 3-hour, even though I did NOT have gestational diabetes.  On my second pregnancy, my hospital-based midwives offered me the alternative of a “casual” glucose test.  I go in for a blood draw (at least an hour after eating normally) once a week for 4 consecutive weeks, and if the results are consistently normal, then the hospital endocrinologists give me the okay.  It’s a pain in the butt to have more blood draws, but it’s working really well for me, and I believe gives a more realistic picture of what’s going on in my body.  

    One caveat, I’ve had to really be firm with the lab, because  this method of testing isn’t terribly common.  The first time I called for an appointment they told me to fast for 10-14 hours.  That wasn’t what the midwife said, so I had to get the midwife to call and confirm with the lab.  Then when I showed up for the blood draw, the first thing they did was hand me the drink, which is not part of this test, and I had to make them check the order again.  So definitely know what test you’re getting and make sure the lab does what is ordered!