There could be numerous possible reasons. If you were smoking often then stopped or slowed down to "every once in a while", this could be your reason. Are you eating a proper meal before? Did you used to drink beverages with sugar in them while smoking (such as soda or other drink with high sugar content) and now don't? Are you sitting in the direct heat while smoking? Are you a diabetic?
You'll always be a "man". The question is, are you a Mans Man?
Just kidding.
