Glucose test question

Mamas who have diabetes! is your doctor having you do the glucose test? I am insulin resistant (not considered diabetic) and I take Metformin every day to keep my sugar levels in the normal range. I didn’t take my Metformin with the glucose test with my first pregnancy and I obviously failed. I monitored my sugar the rest of my pregnancy and found that, duh, my levels were normal as long as I took my medicine. My midwife doesn’t want me to take my Metformin for the test, and I’m sure I’ll fail. I do not want to waste my time taking these tests when I know I’ll fail and I know I’m fine with my medicine. What do I do??