The Importance of the GTT

Now, if you read my birth story, you’ll know I’m not always into every test and medical procedure that is recommended. I question things and say no, which can be very annoying for doctors, nurses, and midwives.


There is one test I have actually asked for early on in both my pregnancies, when it’s usually not routine until third trimester: The Glucose Tolerance Test (GTT) for Gestational Diabetes Mellitus (GDM).

The reason I’m writing about it now is that I see, in pregnancy forums, the same question over and over – “Why do I need to do the GTT?” Statements such as, “I’m not at risk, and I’ll just eat healthily.” “I don’t think the GTT is good for the baby.” “Once upon a time, nobody had those tests, and babies still came out fine.” “There must be another way they can test.” And for those that do get diagnosed, “I’ll just go on insulin, because I want to be able to eat what I’d like.”

I can understand women’s reluctance. I didn’t enjoy the GTT. Like pap smears, nobody ever talks positively about it, so women who haven’t had one yet start to feel nervous and dread it – but although it can be a not-nice experience for a minority, for the majority it’s not really that bad once they do it.

I’ve done the GTT four times so-far – early in last pregnancy (when I was diagnosed), post-pregnancy to make sure it had gone, early in this pregnancy due to risk factors, then a fourth one later to check (also negative).

The reasons why I personally do this annoying little test that only takes a couple of hours out of a whole pregnancy are these:

Anyone can get GDM, regardless of risk factors. Hormones affect different women in different ways. And insulin is yet another hormone floating around, and your particular pregnancy hormones can compete with it. You may have no family history, eat well, exercise daily, and still get it. And not all pregnancies are equal – you might have had one without GDM, and then suddenly have one with it.

GDM is on the rise. It may not have been tested once upon a time, but our diets are so much higher in sugar and carbs, our portions larger. Very possibly many women have had undiagnosed GDM in the past, but it was less of an issue due to home-cooked meals where ingredients were known, there were smaller portions, and people generally had a less sedentary lifestyle.

A “healthy diet” is different to a “diabetic diet”. “Healthy” means different things for different people. Even for the uber-aware label-checkers who know what words like “reconstituted cane juice” really mean, what may be “healthy” for them could be dicey for a diabetic. You wouldn’t tell a coeliac to “just eat healthier”. Diabetes is about more than just avoiding sugar – you also need to be aware of carbs and GI ratings. For instance, that chopped-up banana on your cereal or watermelon for dessert sounds good, but could be enough to tip blood glucose levels (BGL’s) over the limit.

BGL’s need regular monitoring. A GDM diet is not actually one-size-fits-all. Additionally, BGL’s can change throughout a pregnancy – what you might have been able to eat after an early diagnosis is not necessarily what you can still eat later on. It isn’t sufficient to just Google “GDM diet” and follow a rough guideline.

Other factors can make BGL’s fluctuate. Things like stress or illness can impact BGL’s. I noticed if I got so much as a sore throat or had a depressed day, my levels would skyrocket.

The test is safer than the consequences of not being tested. Admittedly, it seems kinda ridiculous – if you have an issue with sugar, which is not healthy for your baby, then why would you then have to drink a super-sugary drink?! But the risks to the baby affected by unregulated GDM are worse than that one occasion of undergoing the test.

The test is currently the best way to discover GDM. Things always change in the medical system, and one day they may come up with an easier way (I hope so!). But the GTT currently is the best way to do a controlled test – everyone does the same fast; everyone drinks the same drink; everyone waits the same two hours without food, water, or exercise.

Uncontrolled GDM is a very real risk to your baby. I’m not a fan of fear-inducing statements generally, but this is pretty important. A lot of people aren’t aware of the risks of diabetes as it is – every time your BGL’s spike, you do a little damage to major organs. Essentially, an uncontrolled diabetic is killing themselves. And when you have a baby on board, that risk extends to them.

When your BGL’s spike and your body’s insulin just isn’t doing its thing, your baby then has to produce its own. Insulin acts as a growth hormone, and the baby’s shoulders can grow disproportionately large, as well as its body producing more fat cells. Fluctuating BGL’s can also put the foetus at risk of its own blood sugar levels not just spiking, but plummeting. In addition, the overworking of a baby’s pancreas whilst still in the womb can lead to later development of Type II diabetes in its own life. (A woman with GDM is also at increased risk of this. Understanding diabetes and learning how to control diet early on can go a long way to avoiding the onset.)

Uncontrolled GDM isn’t that much fun for the mother, either. A lot of women already experience pregnancy symptoms such as excessive thirst, constant peeing, increased risk of infections like UTI’s, and increased risk of thrush. Well, it gets worse with high BGL’s.

It can lead to complicated births and interventions. Speak to anyone about GDM, and you’ll be regaled with stories of, “Oh, I knew someone who had that. Their baby had to be induced early and they ended up with a caesarean.” The large shoulders of a baby who’s had to produce too much of its own insulin can get stuck during birth, let alone the rest of them. This leads to women being induced before the baby’s time would have naturally occurred, possibly needing a caesarean as well, usually at 37 weeks. (Since my baby went naturally to 43 weeks, if she had had to be induced, that would have been six weeks early.)

Also, if a baby has been used to regularly high BGL’s, birth suddenly disconnects it from its source of glucose. Its own BGL’s may plummet, necessitating being whisked away to Intensive Care and put on a drip. (Women with GDM are encouraged to start expressing and freezing colostrum sometime in the third trimester in case of this very reason.)

Controlling with diet if possible is better. It is sooooo hard for a chocoholic to rein themselves in. Believe me, I know. When I had GDM, I ended up avoiding grocery shopping a lot of the time because it’s just so in-your-face. But going on insulin wasn’t something I felt comfortable with, as it is medication, and it does mean you’ll automatically end up under doctor’s care rather than midwives’ and with more risk of birth interventions. A water birth will also be difficult or impossible if you are hooked up to monitoring equipment.

And don’t blame yourself. GDM just simply happens. The stress of feeling you’ve “failed” can make your BGL’s worse. Sometimes some women cannot control GDM by diet alone, no matter how hard they try – and that’s not a failing either. All you can do is try to do your best, but not berate yourself for things you can’t change.

A positive thing is, most people (including myself) say that GDM was actually the best thing that could have happened to them. It forced us to eat healthy, and we lost weight. We felt better and more alert, and felt our babies did too when they came out. We managed to turn a negative into a positive. And we wouldn’t have done that without first doing the test and getting a diagnosis.

The Importance of the GTT

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