You will usually have a overnight fast. With mine I just drunk the full bottle of the stuff( I had 3 choices of favors , grape, lime, and orange) They told me the orange was the least naughtiest of them all so I took that one. (was still sickening)
Blood is obtained before I drank the glucose solution, and blood is drawn again every 30 to 60 minutes after the glucose is consumed for up to how long your test is.
I felt really sleepy,had to pee alot and some what of a upset tummy durning it but that was about it for me.
I hope all goes well for you if you have any other questions please feel free to ask.
