If you have GD which needs insulin to control it (which I understand is only in severe cases anyway) then I think being booted out of the birth centre will be the least of your worries - particularly if it remains undiagnosed. I don't think there's any harm to come from having the test (it's not exactly pleasant, but I imagine you'll be having the 1-hour non-fasting one which isn't as bad as the 2-hour fasting test) and even in cases where it is diagnosed, diet is usually all that is needed to control it.

BW