Just make sure you know your clinics policy so maybe call and ask because some clinics let you eat (just don't eat anything with loads of sugar) and some clinics make you fast but for me, I had an orange flavored drink (some clinics have different flavors or choices for you) but it just tasted like a watered down Popsicle, it was super sugary and almost burned my throat because of the sugar... But it honestly was not as bad as I was preparing myself for. Usually you'll just drink it and then wait an hour and they'll draw blood!
Just don't eat anything high in sugar or super high in carbs before going in. I should of just fasted for my 1 hour because I still failed and had to take my 3 hour. Happened with my first and second, I passed both times the second time around.
its not a big deal they make your drink basically liquid sugar and then they draw blood out of you an hour later and see how your body reacts/comes down from the high sugar levels that they make you drink you'll be fine
When I had my test they drew blood first then gave me drink and an hour later drew more blood and then finally another hour later they drew more blood!
Then you sit there for an hour then get blood drawn.
It's not a big deal. It's a drink that is as sweet as Sprite. You just have to drink it in less than 5 minutes.