Perhaps you could ask your midwife to test for sugar in your urine instead and if there is something concerning then you can have the GTT. This is how GD is tested for in the UK to save women having the horrible drink test without a likelihood of it coming back positive.
Maybe thats what she does? I remember last pregnancy when my midwife came around for the home visits (the other midwife - they worked together as a team) and she tested my urine at every appointment - would this have been what she was testing for?