Diabetes causes changes to blood vessels. This affects the flow of nutrients to your body tissues. It affects how waste is removed from tissues. This can weaken the gums and jaw bone. It can raise your risk for infection.
If diabetes isn't controlled well, higher blood sugar levels in saliva will help bacteria grow. This can cause gum disease. Poor blood sugar control makes it harder for your immune system to fight gum disease. And gum disease may make it harder to control your diabetes.
Smoking is also harmful to oral health. If you have diabetes and you smoke, you're at a much higher risk for gum disease than a person who doesn't have diabetes.