Can You Beat Gestational Diabetes? Decoding the Pregnancy Glucose Screen



The third trimester glucose screen was a mystery to me during pregnancy. When I heard it was a “test,” I wanted to ace it. Diabetes of any kind seemed like something I’d want to try and avoid.

My doctor said something in the way of, “Take this form and go to this lab and get this test. We’ll discuss if there’s an issue.” So I did. I’m not one to question medical authority and questions never seem to come to me until I’m out the door of the doctor’s office. 

I arrived at the lab center very anxious – both for health reasons and personal posterity. Could I have prepared better for this test? How common was diagnosis? What would happen to my baby and me if I had diabetes? Was there effective treatment? All questions I wished I’d asked.

Today, women are diagnosed with gestational Diabetes Mellitus (GDM) at an increasing rate. I’ve had seriously fit friends get it – one a professional dancer! Current research from the American College of Obstetrics and Gynecology (ACOG) states that up to 25% of patients are diagnosed. Patient populations differ drastically, and different practices use different tests and guidelines toward diagnosis – all of which makes the exact incidence tough to precisely quantify.

The screening for GDM can be onerous (multiple tests, 1-3 hours in duration, and all women are subjected to it - not just those at higher risk).

Feeling similarly flummoxed by this looming screen? I spoke to three leading OBGYNs across the country to get answers. 

Cutting to the chase, I can definitively say there is no easy and clearly defined way to “beat” this test (I’m really sorry).

Probably most importantly, for the sake of your health and your baby’s, doctors say you wouldn’t want to. There are serious risks to you and your baby if you develop GDM – particularly if it’s left untreated. The good news is that many future adverse effects of GDM for mom and baby can be prevented with proper diagnosis and treatment.

What to expect at the test?

You’ll likely be screened for GDM between 24 and 28 weeks of pregnancy – sooner if you’re overweight or otherwise at higher risk. There are multiple tests you may be asked to take, again depending on your risk factors and your doctor’s practice guidelines.

The most common test seems to be a one-hour initial screen that does not require you to fast beforehand. When you arrive, you’ll get a concentrated sugary beverage to guzzle – I’m dating myself here but mine tasted like terrible syrup made of orange Tang. In some places you even get to choose your flavor! You then have to sit in the waiting room, fairly sedentary, and wait. I wasn’t allowed to leave the lab - too much movement could affect results.

Your blood is drawn an hour later. You may also be asked to sit for a two or three-hour test with a greater quantity or concentration of the beverage, where your blood is drawn prior to drinking the beverage and then again each hour thereafter.

The test is designed to measure how well your body processes sugar. A high level of glucose means your body may not be processing it properly (positive test result).

If you fail the one-hour screen, you’re asked to return for a longer test. Current guidelines recommend that a single positive result on any blood draw from the two or three-hour tests can be enough to warrant diagnosis.

What constitutes a pass or a fail? The American College of Obstetricians and Gynecologists recently published an updated chart of guidelines for diagnosis in July.

What does it mean?

Evidence suggests GDM is caused by hormones (isn’t everything?!). Hormones from the placenta help our babies develop, but also block the action of insulin in a mom’s body. This is called insulin resistance, and a mom may need up to three times the normal amount of insulin during pregnancy because of it.

The amount of the hormone your body makes increases as your pregnancy progresses – this is why doctors wait to test most women between the second and third trimesters instead of testing right away.

Gestational diabetes develops when a mom can’t make the level of insulin she needs while pregnant. Without insulin, glucose remains in the mom’s blood and can’t be converted into energy.

The extra glucose crosses the placenta as other nutrients do, giving your baby more energy than it needs. That excess energy your baby receives is stored as fat. This can lead to shoulder damage during birth and breathing problems. These babies can also be at greater risk for obesity as children and Type 2-diabetes as adults.

Gestational diabetes also puts mom at risk of c-section, high blood pressure, depression, preeclampsia (a serious high blood pressure condition that can be fatal), and pre-term birth.

GDM disappears almost immediately after delivery for most women, I’m told. However, moms who develop GDM during one pregnancy are at a higher risk of developing it again in subsequent pregnancies. And up to 70% of these moms will go on to develop Type-2 diabetes later in life, according to ACOG.

The CDC created a short but informative podcast on GDM, which may be a helpful resource for those moms who have been diagnosed. It is important to remember that with treatment, many complications can be avoided.


Many factors help explain the increasing prevalence of GDM. As you might suspect, being overweight is a serious risk factor, but you can still be of average weight and not pass the test. Half - yes, HALF! - of women who develop GDM are not overweight. Also surprising: “overweight” is defined as having a BMI of 25 (or above) in studies.  

If you’re into exercise (or if you especially hate it), you’ll be interested to know that several studies actually show physical activity can lead to a higher risk of gestational diabetes in certain patients. Still, most doctors agree that adding physical activity to your routine before and during pregnancy will result in a net lower risk. Recent guidelines suggest working out regularly, but keeping workouts to 45 minutes or under at a time at 60-90% of your max heart rate.

Other risk factors include previous pregnancies with GDM and maternal age. Women 25 and older – but especially women over 35 – are at greater risk. Gaining an excess amount of weight during pregnancy, especially in the first trimester, also increases risk – especially if you started overweight.

The prevalence of GDM is greater among Asian, Latin American, and Indian women, doctors say. Did you guzzle five or more sugar-sweetened sodas a week prior to pregnancy? That’s another risk factor. Gum disease and polycystic ovary syndrome also put you at higher risk, as does snoring. You read that right - regular snorers are at an 11% greater risk versus non-snorers.

Although there is evidence that genetics play a role in developing GDM, there are no defining genetic factors that can be pointed to as the “hallmark” of GDM, I’m told. Lifestyle factors – especially nutrition – are therefore considered to be the key to risk reduction.


The goal of treatment during pregnancy is to keep blood sugar levels normal. Treatment is patient-dependent but generally consists of one or more of the following:

  • Self-administered blood sugar tests: usually 4-5x a day to ensure blood sugar levels stay within a healthy range.
  • Strict diet – lower in carbs and sugar; regular meal times.
  • Exercise – moderately strenuous most days.
  • Medication – between 10-20% of women with GDM need insulin to get their blood sugar in the healthy range. While some doctors prescribe oral medication, data is limited on its long-term safety.
  • Close monitoring of your baby with repeated ultrasounds and measurements. Labor may be induced early as labor after the due date may increase risk of complications.

New recommendations from the American Diabetes Association (as of Jan 1, 2017) are for moms to get tested for diabetes 4-6 weeks after delivery so that results can be discussed at her six-week postpartum check-up. It is also recommended that moms who develop GDM get tested again every year.

Test Tips from Docs

  • Avoid high-sugar foods and simple carbs before the test to help prevent false positives on any of the measures – so maybe no pancakes with a ton of syrup that morning, okay? Eating foods high in dietary fiber could help reduce your risk of developing GDM. Complex carbs may slow down the rate at which your body absorbs sugar.
  • Drink plenty of water before the test to alleviate hunger and also make it easier for lab techs find your veins.
  • Take the test as early as possible during the recommended window (say, at exactly 24 weeks). This may give you lower measures as your body’s hormone levels increase with time during your term.
  • Make your appointment first thing in the morning (for those who are doing a fasting test) so that you won’t have to fast during the day.
  • Bring a book – one to three hours is a long time to spend in a doctor’s office or lab.
  • If you’re against drinking the sugary beverage provided for any reason, by the way, (chemicals or otherwise), there are at least a few alternative tests you can request. One requires eating 28 jelly beans in one sitting! Another is finger stick blood testing, which can be done at home. Keep in mind that these alternatives are not as accurate or well validated as they’re harder to standardize.
  • Don’t try to cheat the test – if you have GDM, you want to know and treat it!


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