Glucose Tolerance Test

I'm 28 weeks pregnant and just failed my 1-hour glucose screening (result was 150). I'm scheduled to take the 3-hour GTT. I was instructed to, on each of two days prior to my test, eat 6 slices of bread or 3 candy bars. Then I'm to fast starting at midnight the night before the test (my test is at 8 am).

I'm confused. Why load up on carbs, including simple carbs like in the candy bars, in the days preceding the test. Won't that just increase my risk of a false positive result?

Also, what are my chances of failing the 3-hour test given my 1-hour results, the fact that I have no family history of diabetes, I did not have GD with my first pregnancy and I am relatively small-framed (was 5'4" and 112 lbs prior to this pregnancy).

Thank you!

[JDRF-Team-sgg]

This request for the carb overload the night before the test is not one I have heard before, although I am not questioning it as a way to check to see what your body is able to handle in the way of carbs. Most of the glucose tolerance tests I have heard of involve drinking a nasty sweet syrup to do the carb overload and then testing glucose at several different times after consuming the syrupy beverage. Your doctor's request for you to eat the high amount of carbs in foods the night before actually seems to make more sense, for it gives your body longer to react to the sugars than the drink-the-syrup-and-then-test method. So it may be a truer indictation of what your body is actally able to do in an extended period of time.

Doing this will increase your chance of a positive only if your body is not able to produce enough insulin or if your hormonal situation is making you insulin-resistant while pregnant (which is the usual root cause of gestational diabetes).

As for the three hour test, this will show if your body is reacting properly to the stimuli of carb overload by producing added insulin. Please discuss this with your doctor and ask him or her to clear up the reasoning behind the request, and I am sure that he or she will give you answers that make good sense.

I do hope that all the tests come back well. Even if you find out that you are dealing with gestational diabetes, you can probably easily treat this and then go back to normal once your baby is delivered and your hormones are normal again. I do wish you the very best. Try not to worry over it -- it sounds as if your doctor is taking very good care of both you and your baby.