"To me, cigarettes are food."
-- Frank Zappa in response to an assertion that his nicotine habit conflicted with his anti-drug stance
I'm diabetic. So whenever I eat or drink something with carbohydrates (i.e. just about anything besides water), I take some insulin.
Also, recently I've taken up smoking. And more than once I've found myself wondering, while opening a pack of cigarettes, "How much sugar is there in this? How much insulin should I take?"
Then I remember it's a drug, not food.
Actually, cigarettes do, in fact, contain sugar. aurel42 tells us this in Nicotine might not be the most harmful ingredient of tobacco. Of course, it is not absorbed by humans when smoked.
However, smoking a cigarette has been shown in studies to slightly elevate blood sugar (apparently because it raises adrenaline levels, causing glycogen stored in the liver to be turned into glucose and released into the blood stream). Maybe that feeling was right after all.