I've just upped my consumption of green tea.
I like this a lot better than black tea because it tastes nice with a bit of lemon juice and no milk and I still can't really enjoy black tea without sugar (so no black tea).
Because this is a change in my diet I thought I had better Google it to make sure there were no adverse effects on diabetics.
However it seems that green tea may have positive benefits for diabetics.
For example
http://www.biomedcentral.com/1471-2210/4/18 has some encouraging words hidden amongst all the jargon.
It seems possible that green tea may reduce insulin resistance because it can reduce blood glucose without increasing insulin production.
Loads more references as well.
I looked for a thread specifically about this but was more or less defeated by the search function.
This is the nearest I have found.
Anyway, loads of gree tea for a while.
Cheers
LGC