Ladybirdflies - look up the risk factors for gestational diabetes, as well as the effectiveness of the glucose test, and make your decision from there.

I've skipped mine the past couple of times, and my first midwife was not OK with that, but I was confident in my decision. (She said "Well, the only other person I've had who skipped their diabetes test had a stillbirth... Good grief.)
My second midwife said that since I was very low-risk and had no history of large babies or any other indications of GD she was fine with that.