What is the glucose tolerance test (GTT)?

The GTT is a medical test that measures your body's ability to regulate blood sugar levels after consuming a sugary drink.

Why do pregnant women have to take the GTT?

Pregnant women are at a higher risk of developing gestational diabetes, so the GTT is used to diagnose and manage this condition.

What is the hemoglobin A1c (HbA1c) test?

The HbA1c test measures your average blood sugar levels over the past 2-3 months and is often used to diagnose and manage diabetes.

Can I opt for the HbA1c test instead of the GTT?

It depends on your doctor's recommendation and your individual risk factors. Some women may be able to opt for the HbA1c test, but others may need to take the GTT.

How long does the GTT take?

The GTT takes several hours to complete, including the time it takes to drink the sugary drink and have your blood drawn several times.

Yes, the GTT involves multiple blood draws, which can be painful and uncomfortable.

The Ultimate Test: GTT or HbA1c? Why Pregnant Women Are Forced to Suffer Through GTT Instead

Hello there!

I'm 24 weeks pregnant, and my doctor suggested I take a glucose tolerance test. It's usually done for pregnant women to detect gestational diabetes early on. The test is mandatory, but that doesn't mean you can't opt out. I met a girl in the waiting room who refused to take it, saying her doctor just asked if she was coming, and she said no. I decided to go ahead with it because I had a family history of diabetes, so I wanted to get tested.

Before the test, I read some reviews, and I was mentally prepared. To be honest, the test wasn't that hard for me, but it wasn't because of my prep work – it was because my husband came with me and kept me company. He knew I was going to be there for a while, so he brought a book, a magazine, some knitting, and a show to watch. I brought a smartwatch, the Amazfit GTR2, with a metal band, which I've had for four years now, and I've never regretted buying it.

Preparation

You don't need to do anything special. The test is done on an empty stomach. It's recommended to fast for 8-10 hours beforehand. Try not to overindulge in sweets the day before, or you might end up with a high glucose level and a GD diagnosis.

IMPORTANT! Try not to stress out, although I think that's impossible in our city. The thing is, when your body gets stressed, it goes into 'fight or flight' mode, and it needs energy. Since the test is done on an empty stomach, it's going to take that energy from your liver. And your liver will give you glucose, and a lot of it. The doctors won't be able to tell the difference right away and might diagnose you with GD.

What to bring

🍵A cup or a small container. It's not necessary, but drinking the sweet syrup from the pharmacy bottle with a narrow neck is way less comfortable than drinking it from a regular cup.

🍋Lemon wedges really help with nausea. I also used them when I had to drink a liter and a half of Fortrans during my pregnancy. I also use them to make my water more acidic, which I still do today. Just be careful if you have any stomach issues.

🍭Glucose from the pharmacy, if they don't give it to you at the lab. We got it for free at the lab already mixed. Glucose from the pharmacy is what you need – no chocolate bars will do. It's food.

🥤A water bottle is a good idea to bring to rinse your mouth after the sticky syrup and drink properly AFTER the test.

Snack time immediately after the test. A slice of bread, a glass of water, a protein bar, an apple – what's convenient to quickly munch on right after finishing the analysis, because hunger is screaming at you. I didn't bring anything with me, because I usually manage to get through a short fasting period, but not in this case.

How a glucose tolerance test is conducted?

First, they take blood from a vein to check your blood sugar level before the glucose load. If your sugar level is above normal, the test is over. This immediately means you have gestational diabetes, and your next appointment will be with an endocrinologist.

If your sugar level is normal, they give you glucose and have you sit on a couch for an hour. Then, they take another blood sample from a vein and have you sit back down in a state of hypodynamia. An hour later, another blood sample from a vein, and you're free to go.

A bottle from the glucose drink for the TGG test

What not to do during the test?

You can't eat.If you get sick after taking glucose, the test is cancelled/rescheduled for another day.You can't drink water.You can't move.As for the first two points, I think it's pretty clear, but we'll have to dive into the mechanics of the process for the last two.

As far as I understand, the body can get rid of excess glucose from the blood in several ways:

Muscle activity, i.e., you ate a candy bar, moved around, and your blood glucose level decreased;A large amount of liquid helps to remove glucose from the urine;The liver excretes glucose and makes glycogen;The pancreas produces insulin, breaking down glucose.The first two methods are the most beneficial for the body. However, the test is conducted precisely to see how the liver and pancreas work.

So, if you drink and/or move during the test, your body will get rid of the glucose through water and/or muscles, respectively, making the test non-indicative. Unfortunately, not all lab technicians explain this in person. While it's not the most obvious thing. We had one girl who instinctively started walking down the corridor because she couldn't sit still. Thanks for at least mentioning the no-water rule.

My experience

First of all, I'm not very satisfied with the work of our free women's consultation, so I try to avoid it altogether when I'm not pregnant. The only good thing is that the appointment and the test start on time.

My analysis started at 7:30. There were three of us pregnant women, and we all arrived on time. We gave blood, sat down on the couches, and waited for almost an hour (!) for the blood to be checked for sugar.

Then, they brought us bottles with a warm solution. It's approximately 150-200 ml of water and 75 ml of glucose (totaling around 300 kcal). The solution looks like a thick sugar syrup, a bit like a liquid jam in a cup. You have to drink it within 5 minutes. I didn't pull any punches and drank it in three sips with short breaks. Then, the mighty lemon came to the rescue.

Immediately after taking the glucose, I didn't feel any terrible sensations. By the way, my hunger pangs disappeared, and they came back only an hour later. However, about 10-15 minutes after consuming the solution, I think it was when the gradual absorption of the liquid started, there were mild hints of nausea. Again, the lemon came to the rescue.

I have to say, the first hour under stress was the worst, but after that, it got easier. I had to give blood and wait another hour for the next draw.

I had blood taken from the central vein in my left hand, almost from the same spot all three times. The first prick was normal, almost painless, the second was a bit more sensitive, and the third was unpleasant. I could feel that the blood-drawing site was already traumatized. Why couldn't they take it from different veins (I have three working ones), I don't get it. I guess it was just easier for the lab technician to work with the central one. Again, who cares about patient comfort in free clinics?

A healthy crater in the vein after the glucose tolerance testI had a serious episode of hunger already at home. I came back with a hot, fresh samosa just out of the oven, and I realized I couldn't take it anymore. I just took a bite, and my vision started to blur, and then I felt cold sweat all over. In short, I was writhing in agony for 10 minutes, eating a vegetable salad, drinking tomato juice, and finally, I sipped on some freshly brewed coffee and stretched out on the couch with a book. Kaieeeef.

It was during this intense dopamine rush that I realized my body was severely stressed out from skipping two of my usual breakfasts due to the test. Let me repeat: bring a light snack with you. Even if you don't feel hungry at the end of the test, by the time you get home, you'll be ready to kill for food.

Glucose tolerance test: normal values

<5.1 mmol/L fasting;

<10 mmol/L 1 hour after glucose load;

<8.5 mmol/L 2 hours after glucose

My results

4.2 fasting;7.7 after 1 hour;8.3 after 2 hours.Normal, although the last reading looks a bit high to me. By the way, I got my results 3 weeks after the analysis – almost 28 days later. Very prompt, considering the possible GDM.

Why was I diagnosed with GDM?

Because, after a month and a half after the GTT, my next blood draw for glucose showed a value 0.14 mmol/L above normal. GDM is diagnosed from 5.1 mmol/L, and I had 5.14. This was the only time during my entire pregnancy.

It's worth noting that I don't have excess weight, my BMI before pregnancy was normal, and my weight gain throughout the pregnancy was smooth and predictable, with the baby gaining weight, not me. After giving birth, my weight returned to what it was before pregnancy. I also didn't have any symptoms of diabetes, I felt great from start to finish, but the main thing is that my diet is well-balanced, with no excess carbohydrates, including fast ones.

I should have seen my face when the gynecologist cheerfully slapped me with a GDM diagnosis due to a single, insignificant spike in glucose, and then, without consulting an endocrinologist, prescribed a diet for diabetics (an evening diet with strong restrictions on fats, proteins, and carbohydrates!) as a panacea for all my problems, instead of sending me to Invitro to test my glycated hemoglobin. Given this, before starting a diet with questionable consequences for the baby, I decided to take matters into my own hands and get tested again.

Glucose Tolerance Test or HbA1C?

When I suspected I had gestational diabetes, my doctor ordered a glucose tolerance test, which is supposed to be the most accurate for diagnosis. It shows the average blood sugar level over the last three months.

The glucose tolerance test shows how well my liver and pancreas handle excess glucose in my blood right now. Are they coping with it or not? But here's the thing.

Gestational diabetes usually starts developing around 15-20 weeks of pregnancy, so by 24-28 weeks, my HbA1C would already be above normal. And, more than likely, I'd be showing symptoms of diabetes:

thirst;

polyuria;

craving for sweets;

muscle weakness;

excessive fatigue

The glucose tolerance test would only show normal levels if gestational diabetes started developing yesterday, and I got my blood test today. In all other cases, it would be obvious.

What's more, the glucose tolerance test is a lot more complicated than just a simple blood draw. I had to fast for three hours, sit on a hard chair, and drink a sugary drink. It was a real ordeal.

So, why do doctors still order the glucose tolerance test? Because it's cheaper than the HbA1C test, that's why. The test itself is okay, but the way healthcare providers approach it makes it completely useless.

Firstly, it's a complicated test to perform. It's easy to mess it up: you can't eat, you can't move. And the lab technicians themselves often don't understand what they're doing or why, so they can't even offer proper guidance. So, how informative can the test results really be?

Secondly, why bother with the glucose tolerance test if a slightly elevated glucose level is already a reason to put a pregnant woman on a strict diet? Just monitor your glucose levels every two weeks, which is a simple and cheap test. Why go through the hassle of a three-hour ordeal?

And thirdly, there's the HbA1C test, which is just as informative but much easier to get done. You can even do it yourself at Invitro. So, why not just stick with that?

Honestly, if I had to go through the glucose tolerance test again, I'd refuse and get my HbA1C test done at Invitro instead. I wouldn't go through that three-hour ordeal again.