Apr 13

What NOT to eat before your Glucose Tolerance Test!

The test to check if a mother has Gestational Diabetes asks the mum to take 75gm of sugar after skipping breakfast. That's the equivelent of two cans of coke as your first meal of the day. As you can imagine, if your already have high blood sugar levels before the test, then you are potentially going to get inaccurate results.

What does it mean if you have gestational diabetes?

In our everyday lives our bodies take the food we put into our mouths, digest it into it’s smallest components, and then transports it into our cells. Here it is used to fuel the cell so it can do all of its various jobs. So, we really need all of this good fuel to keep us going.

The body’s preferred fuel is glucose, and that's where it works with the pancreas to produce something called insulin. Insulin’s job is to transport the glucose from the blood stream through the cell membrane and into the cells where it can be utilised. So think of glucose as the passenger and insulin as the key to unlock the door to the cells so that the passenger (glucose) can get through.

What may be happening when a woman is pregnant is that the pancreas is simply not making enough insulin (not enough keys), and the other is when the cells become insensitive or resistant to the insulin. In effect the keys aren't opening the door anymore. Both scenarios lead to higher than normal glucose levels in the bloodstream and the unwelcome side effects we associate with diabetes. The fuel is of little use outside the cells, so in diabetes, we have too much fuel but at a cellular level we are starving.

How does gestational diabetes affect your baby?

During pregnancy, the placenta produces hormones that can interfere with insulin's normal functioning. This means that because the passenger can't get into those locked doors, they are stuck in the mother's bloodstream. The excess glucose in the blood can cross the placenta and enter the baby's circulation. This can lead to the baby's pancreas producing more insulin to process the excess glucose. The baby's pancreas may become overworked, leading to an increased risk of fetal macrosomia (large birth weight) and possibly a low blood sugar level at birth.

The good news is, this is usually managed with a simple diet and most women keep their levels under control. Some women may need assistance with insulin injections until after birth.

Most women, will return very quickly to their non-diabetic state post birth unless you are one of the women that had undiagnosed diabetes prior to pregnancy. 

Booking your glucose tolerance test

Normally you would recieve a referral from your midwife or caregiver around 26-28 weeks and are encouraged to attend before your next appointment. Please not you don't have to take the test if you don't want to (more on that later).

The test is administered by you fasting from about 8pm the night before. This means you can only have water and no breakfast. You will have your blood taken when you arrive to test your baseline glucose level & then you will be asked to drink the glucose drink.

After one hour of waiting in 
the collection centre a further blood sample will be taken. After another hour of waiting a third blood sample will be taken.

You will usually be 
contacted soon after if your test results are abnormally high, otherwise it will be discussed at your next antenatal visit. Usually no news is good news!

How to pass the glucose tolerance test

The GTT is not a pass or fail in your pregnancy. It is simply a determination how well your sugars are being absorbed and if there is a cause for concern. That being said there is a lot of evidence out there that we shouldn't be testing every woman and there are questions as to whether it's actually the best way to gauge the true state of your insulin levels. Nonetheless, this is the usual way that women are being tested for gestational diabetes and most women are taking it so let's make sure we can get you an accurate result.

If you can practise this during your pregnancy then amazing! Otherwise, if you 
a) have a pretty similar diet you can be a bit more strict for about 4 days prior to the test
b) have admittedly poor diet or you don't eat regular meals due to feeling sick or being on the go, then I advise starting this at least a week before.

What to eat before you glucose tolerance test dates

Focus on eating Real Foods. This means try to make things from scratch, avoid packets and anything try not to eat takeaway meals.

What to eat

Don't miss breakfast and spread the meals out throughout your day. You want to balance your meals with protein, carbohydrates (the good ones), leafy greens, vegetables and fruits with low fructose. Plus you want to be drinking plenty of water (2-3 litres per day)


lean meats, poultry, fish and seafood, quality dairy
Carbs & Good Fats 
lentils, quinoa, sweet potato, avocado, beets, pumpkin, non starchy vegetables, nuts
Vitamins & Minerals
Broccoli, spinach, cabbage and broths, low fructose fruits and vegetables.

What to avoid

Processed foods (things in a packet), refined carbohydrates (white bread, pasta, pastry), trans fats (margarine, commercial baked goods, fried foods), sugars (this includes high fructose fruits) and sweeteners

Prioritise Sleep & Exercise

You'll be surprised how much a regular bedtime (before 10:30pm) and a solid eight hours will do for your health. Not only will you wake up feeling fresher after a few days of going to bed on time, but there are health benefits to your glucose levels too. Your glucose levels need to be munched through while you are sleeping, so you if you don't get the needed rest then your body doesn't process what's leftover from the day before.
Make sure to do 30 minutes of active movement per day during pregnancy. This can be as simple as a walk or swim. 

Alternatives to glucose test during pregnancy

  • Get your HBAC1 Tested First - this is a blood test which measures your blood glucose metabolism and is a standard test for diabetes. If you come in the higher range then you can determine if you should take the test. Discuss this with your midwife or OB.
  • Measure your own glucose levels - Buy or borrow a glucometer and log for two weeks your diet and levels to ensure everything is on track. You can show this to your caregiver to put their mind at ease (but you don't have to).
  • Decide not to test unless you have symptoms - You can take a different approach and choose to look out for the abnormal signs of higher than normal sugar levels. Speak to your doctor/midwife about this option, but it may look like dizziness, headaches blurred vision.

What do I do now if I have gestational diabetes?

If you are going public then you will simply be referred to the clinic in your hospital that cares for GDM mums. You will see an endocrinologist and a nutrionist to help you manage your diet or, if needed, work out how much insulin you need to take. Most women will simply record their blood sugar levels a few times a day and be on a special diet.

A great book to get started with is, Real Food for Gestational Diabetes by Lily Nichols. She gives some alternatives to the "old school" diet restrictions still practiced in hospital and perhaps it resonates with you and your belly.
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When you have gestational diabetes, sometimes you are asked to change your birth plan, but with the right research and support, you don't have too! It's all there in Unit 4 of BirthTools™

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