Almost passed out, should I be worried?

I finished my 1 hour glucose test about an hour and a half ago (which I fasted for) I drank Gatorade and ate a pop tart when I got back to my car, and ate lunch shortly after. About 15-20 minutes after I ate, I was still sitting at the kitchen table and I got really hot, everything went blurry and started going black, I saw white stars and totally lost my hearing. I got really weak and almost threw up and barely could walk to the bathroom. I laid on the bathroom floor for a few minutes and it all went away. Has anyone had this happen? Could it be from the glucose test or something else? Should I be concerned?