Gtt test

[elizabeth27]

Hi all
I am 28 weeks and where I live everyone has to have the glucose loading test- however it says fast from 9pm the drink 410ml of lucozade two house before appointment where they will take blood. No bloodtest beforehand! So how do they know what your base level is?? Is this normal? Thank you x

I get so confused about this test - I just had a blood test and it came back with normal sugar levels (I'm 33 + 4). No GTT. Why does every woman have to have it where you live?

Do they take blood twice, once just after you drink the sugar and then once after two hours?

When I had a gtt, the midwife took blood, then gave me the sugary drink, then took blood for a second time 2 hours after the drink.

I would query the instructions you've been given just to be sure they're not wanting to take blood before the drink.

It sounds like you're having the simplified test, which is what I had. You fast (mine was from 7pm), then 7am the next morning have the lucozade and then then blood test at 9am.
I did it wrong the first time (no fasting and had crunchy nut cornflakes about 30 mins before the blood test) and my blood sugar level was sky high! I did it right (with the fasting) the second time and it came back normal.
Your test sounds normal for my area, from what I understand you only have the other test if you need a re-test.

I don't know anything about these tests, but it doesn't seem unreasonable to only have the one blood test. If things are functioning properly, your body should cope with the sugar appropriately and your blood glucose level will be in the expected range. I wouldn't have thought they'd need to know a before and after, as it's the absolute amount of glucose in your blood that's of concern.

When I did this test last year I had a blood test, then drink, then blood test.

There must be two different types of them.

I work in diabetes care & we use the standard GTT i.e. Fasting blood glucose followed by another glucose level 2hrs after sugary drink. If either level is diagnostic, you have GDM.

In the US they have 2 different kinds, the Glucose Challenge Test (GCT) and the Glucose Tolerance Test (GTT).

The GCT is first and consists of fasting for 12 hours and then drinking the drink and then taking your blood and checking your levels. If that test flags as positive, then they'll have you do the GTT.

The GTT is fasting, take your blood, drink the drink, take your blood after and hour, then blood again at 2 hours and blood again at 3 hours. If any of those are positive you're diagnosed as having Gestational Diabetes.

I've had a version of the GCT in the U.S. I was told not to fast first, just eat normally and not for the hour before the test time. Then I had to drink a very precise quantity of a glucose drink (every drop consumed inside 2 minutes) and a stopwatch was set for 60 minutes. Blood was taken when the stopwatch went off. No need for baseline blood as the idea is to see how you process X amount of sugar in a set time. Not a before-and-after scenario.

This is the initial screening test, which has a very low false negative rate but a higher false positive rate. It means that if you have diabetes, it is virtually certain you will fail the test. However it also means a certain number of people who don't have it, will also fail, hence the high false positive. So it is used only as the simplest initial mass screening and then a second-stage full GTT is carried out on the people who failed the first screen. That test involves strict fasting and more sets of bloods, so is less convenient and more demanding on patients. When carrying out mass screening, it makes sense to have the two-step process with most people simply doing the cheaper, most convenient option, before applying the more complex test only to those likely to be diabetic. In other healthcare systems, where they only screen for GD if you already have risk factors, it makes sense to go directly to the more sensitive diagnostic test without the initial screen to weed out large numbers.