Can I tell my doctor hell no.

I'm on government insurance. I passed my glucose test with flying colors, I have family history diabetes so she said my next visit I have to do a glucose test again! The first time I did the glucose drink I was sick for three days after felt horrible if you look it up its ingredients are almost super sugar wth I don't want to do it, I think it's unnecessary and I feel fine is there any way I can go against doctor visits? I shouldn't have told them anything this is why people don't say anything to doctors I understand why she wants to but look if you are healthy you feel healthy and you know you got this why get tested and screened for something you don't have plus you already passed one test I sound like a baby but dam I was really sick drinking that stuff last time it put my body through hell