I was wondering what a 'normal' reaction to the test would be and what a 'diabetic' reaction to the test would be after drinking the glucose water. Do the effects of the glucose linger for hours or do they go away quickly? Any insight?

Here is a link showing the medical possibilities in a glucose tolerance test:

http://hypoglykemie.nl/gtt.htm

One thing doctors don't always attend to are the lows.
If you can get the results, and compare yourself, you might learn more. A 2 hr GTT test is not long enough to show all the lows.
The green line shows reactive hypoglycemia. This type of response is sometimes used to predict diabetes later.

I read mrsD's link with curiosity and some surprise.
My test was done at an outpatient blood-draw lab. It was never mentioned to me that a carbohydrate-rich diet should have been partaken 3 days before the test. I've been on a low carbohydrate diet (maybe 50-100 mg) since well before my test. I know I made the neurologist aware of that, and the technician administering the test (because she had asked me for a copy of the diet, which I gave her when I went for the test) but it wouldn't surprise me if neither doctor nor tech. were aware of this instruction. They were also aware I was taking a diuretic (40 mg. furosemide) and aspirin (1/day).

I will say that I was expecting a bit of a sugar rush of some kind, particularly having the test done on an empty stomach after fasting, but I experienced nothing at all in that respect. I felt normal (albeit hungry) the whole time.

I was also told I could leave, drive home and come back later for the subsequent draws.

If I'd known some of this before the test, I think I might have had some discussion with the neurologist...

Doc

I had both of mine done in an outpatient hospital clinic.

The risks increase with people with seizure disorders, or who are already diabetic.

Screening relatively healthy people for trending or fine tuning, is relatively safe. I had a 2hr one done in the OB office looking for gestational diabetes, which was negative.

My second GTT which was a 4hr, I "lost" it near the end. Shaking crying, and pain from the needle sticks and low readings... which my veins created a very painful experience.

Also notice that the website is in Holland... a European opinion therefore. Other countries have different points of view and differing
activities in clinics and offices.
But doing the long test is definitely not safe at home for some patients.
Finger stick testing is less accurate as well, and will not give the same results.

IMO in diabetics the glucose may remain around for a while depending on medication routines. In non-diabetics, it is typically low by the 2 hr mark.

--I feel that one has to try to get such testing done in an environment that is not likely to skew the results.

To that end, I don't necessarily think eating a carbohydrate rich diet a few days before the test is a good idea, if that is not what one normally does. Then, too, I don't think eating a very carbohydrate restrictive diet a few days before the test is a good idea, either, if that is not what one normally does. I think either might skew the test results somewhat. I do recognize that there are many people out there on special diets who might need to explain this to their physicians before the test.

There are various meds that do skew the results, and these should also be mentioned to physicians before the test begins. Anything that might interact with the rate or completeness of glucose absorption might alter the results.

One thing I do know--during the test, one should not do strenuous, or even not so strenuous, physical activity. That DEFINITELY alters results. (I'm amazed they let you go out and return, Doc, as they'd have no idea what you might have been doing during the absences. When I get the tests done, I know to bring a book or an ipod or something for the duration--I'm not going anywhere until the test is done.)

I still think that a more optimal glucose tolerance test is longer, with more frequent blood draws (half hour instead of an hour, in order not to miss rising/falling levels/patterns) and with insulin levels measured along with glucose levels. I have mine done for 4-5 hours. I admit this is not easy to tolerate for most, and the constant sticking--one can get stuck 9-10 total times--is a drag. I do alternate arms, and try to come in well hydrated, so there are different spots to access veins as time goes on.

What one is looking for is not only the glucose levels over time, but how they rise and fall in consonance with insulin levels. Even a fasting insulin level may be an interesting piece of info.

I asked them if they couldn't just leave a line in.... They know me (or my veins) well enough by now that there are only 2 phlebotomists they'll allow to work on me. Combination of really deep, hard to find, harder to penetrate veins combined with a horrendous case of trypanophobia. I think for that test they finally found one on the back of one hand, but it took a few tries, and I was extremely hydrated, cuz I hate when they drill...

Doc

Some tricks:

1) have the phlebotomist use a butterfly needle on small veins.
It makes a big difference. I also give out of the hand as I have one vein that works sometimes.

2) If you inflate a blood pressure cuff on that arm instead of that stupid rubber band thingy, it often pops the vein better.

3) some places have the new machine that scans for veins.
http://www.accuvein.com/

There are some other tricks on this site:
http://www.phlebotomypages.com/exper...m#.T47jdNnPzPM

Being well hydrated makes the process easier.