Eh sayang, honestly the glucose tolerance test (air gula tu) is just to check, bukan untuk elak, it's a screening tool so the doctor can see how your body handles sugar, cannot really prevent it mah. A few of us tried cutting sugar before our tests thinking it'll help, but actually the test result won't change because they're checking your baseline! Best thing is just go for the test fasting like they ask, eat normal before that, and let the doctor do their thing, if you're worried about gestational diabetes overall, that's a good chat to have with your OB about diet and lifestyle lah.