When I was in my 2nd trimester and had the standard round of blood tests by blood sugar level was also high. I then went on to have the 2 hour GTT test and was fine. I do remember on the day I didn't have breakfast and then had some white bread for lunch with soft drink (I don't often have soft drink and usually always have wholegrain bread) so it is possible the choccy milk might have influenced the test.

Make sure you follow the instructions with the carbo loading before the test so the results are accurate but a high sugar level doesn't always mean GD. If you don't mind please let us know what happens.