Glucose tolerance test

Who's had to have this test done? I started off this pregnancy with a high bmi but I've lost a fair amount of weight over the past 5 months mainly due to not being able to eat the first 3 months and then not wanting anything sweet to eat or drink since then... I'm pretty sure that because of my starting bmi i will still need to be tested 😞 what can I expect? I keep hearing horrible stories and it's making me nervous, I'm not great with blood tests and not eating first thing in the morning makes me feel really sick so all in all it sounds really poop, I keep telling myself it's all for the baby but when you have a sickness phobia that's easier said then done