to the best of my knowledge no it doesnt, they will be wanting to test her normal blood glucose and normally the body should be able to control and maintain blood sugar levels at all times.
I think another type of sugar test (fructosamine) is one where they need to be fasted but that is normally only done if theres problems after a normal blood glucose and in diabetic management.
Check with your vet though, i'd imagine they'd probably say dont feed brekkie etc but cant see why starving is nec..defo dont withhold water.