Coke Zero.
Something that is delicious though (as disgusting as it sounds) would be half a cup of diluted Orange Juice (preferably Robinsons) topped up with Diet Coca Cola
As for alcohol, even though I'm a second year, I'm still completely new with it and I know what I will be avoiding (the only alcoholic beverage I've ever had) - Guinness. Yuck. I guess part of the reason I'm nervous around alcohol is I don't really know the extent to which it would affect my diabetes because you can have a hypo whilst drinking and not feel the usual symptoms, which makes it all the more dangerous - I know the worst case scenarios are fit/coma/stomach pump. From what I've heard though Beer/Lager is best for diabetics. Things like wine can send it extremely high, whereas stuff that is high in alcohol like vodka is ok in moderation but it will lower your blood sugar rapidly. Beer/Lager contains carbohydrates so it will temporarily raise blood sugars, but they will drop rapidly so pay attention to your blood sugars if you are a diabetic and test regularly!