It never even occurred to me that caffeine could affect my blood sugar until this past weekend, when I had a conversation with a fellow diabetic who told me she has to bolus 0.5 units for a cup of coffee. I always thought it was a "free food"! Well, I still think it is, for me, but maybe it's different for different people. I've never noticed it to make a difference in my blood sugar. Now, if I'm drinking a lot of it because I haven't slept, then my sugar goes up. But I think that has more to do with fatigue.