Early Gestational Diabetes Test?


I'm 14.5 weeks and my doctor wants me to go in for an early Gestational Diabetes test sometime this week. I didn't think of it at the time, but apparently it's a fasting test. I've been very consistently super nauseous and vomiting if I don't eat something first thing when I wake up in the morning, which has me a bit concerned.

What would you all recommend? If I end up vomiting during the test, would that invalidate results and I'd have to do it again? Anyone have any experience with this?