3 hour glucose test

I just got told I have to do the 3 hr. I did the presceening yesterday and almost passed out. I'm sure I'll be unconscious for the 3hr! The nurse told me if the next one comes back bad...all they will do is send me to diabetes education and modify my diet. Has anyone had negative results? And what do you have to do? Also..:does the 3hr cost more?? I'm just trying to figure out if I can get out of it. I don't want to do the test or spend the money!