How unhealthy is it to drink a cup of coffee with each meal?

I was doing well with eating a low carb vegan diet and exercising a few hours daily, but suddenly that's not enough to keep my blood sugars in line.  I have not been a coffee drinker (I don't really like it) but the other day I was desparate for both warmth and energy so I drank a cup -- and my blood sugars dropped dramatically.  I bought a jar of instant and have been allowing myself to drink one cup a day -- after which my sugars are good :) until the next meal.  Which would be worse for my health, returning to insulin useage or drinking  more coffee?  FYI, I also already take all of the natural remedies of which I am aware and to which I am not also allergic -- which is why I can't take any oral meds other than the amaryl.

Thx,

Insulin Free