The blood vessels of patients with diabetes are more vulnerable to the harmful effects of cigarette smoking. The toxins in cigarette smoke can damage the smooth lining of the body’s arteries. At the same time, too much glucose in the blood from diabetes damages those same blood vessels. As the blood vessels accrue damage, they become more susceptible to forming plaques - build-up of a fatty substance on the artery wall. These plaques can narrow blood vessels or break so that clots can form to cause heart attacks.