I haven't tracked anything, but do drink lots of fruit tea.
Fruit tea probably wouldn't have an effect on blood glucose. There are no carbs/sugars in these teas, hence no sugar to get shuttled into the blood stream. Even artificial sweeteners, which could possibly raise insulin due to sweet taste, seem to have little effect in reality:
http://www.marksdailyapple.com/artificial-sweeteners-insulin/
So naturally-flavored, no-carb fruit teas probably would not affect blood sugar. (unless they made you hungry and caused you to eat sugar!)
