Perhaps one of the largest contributors to gum disease in recent years is smoking.  Smoking, like diabetes, causes the blood supply to the gum tissue to decrease, leading to lessened healing.  Remember our mouth usually heals rapidly when compared to tissue outside of our mouth.  With less blood supply, gum tissue is more easily overrun by bacteria.  Also, smoking can cause a dry mouth, which the bacteria love:  they grow more rapidly without saliva to wash them away.  Finally, smoking is one of the leading causes of oral cancer.
A crash course in the process of gum disease is as follows:  first, the bacteria build "soft houses".  This is the fuzzy feeling on our teeth that we want to brush off when we notice it.  If given enough time, the bacteria build "hard houses" otherwise known as tartar, or calculus.  This is similar to the build-up found in old plumbing.  Most of us will remove the bacteria when we feel the fuzziness, but when gum disease is present, we cannot clean deeply enough to remove all the bacteria, so they are free to keep building.  This, in turn, causes more swelling and deeper pockets, which trap more bacteria.  All of this bacteria must be cleaned out by a professional at your dentist's office.
There are resources to help you quit smoking, which will save your mouth from the nasty side effects and definitely cost less from both the cost of buying smokes and the cost of repairing the damage done.