Smoking Cessation Health Center

Cigarettes May Raise Your Risk of Diabetes

Aug. 1, 2000 -- Doctors have long known that smoking can increase the risk of complications of diabetes, such as heart attacks, strokes, and serious circulation problems in the feet and legs. Now results of a study conducted in Japan suggest that smoking may raise your risk of developing diabetes to begin with.

"I think this is another nail in the coffin of smoking," Christopher Saudek, MD, president-elect of the American Diabetes Association, tells WebMD. This study "is interesting because they tied smoking not to the complications of diabetes, but to the risk of developing diabetes. That was something that was news to me." Saudek, a professor of medicine at Johns Hopkins University in Baltimore, was not involved in the study.

Researcher Noriyuki Nakanishi, MD, and colleagues followed more than 1,200 male Japanese workers for five years. As required by Japanese law, the workers underwent a health exam each year. Blood samples are drawn as part of these exams. Employers are permitted to release anonymous data from the exams for research purposes.

Type 2 diabetes occurs when the body becomes resistant to insulin, the hormone that allows blood sugar to enter the cells so they can use it for fuel. The sugar builds up in the bloodstream, leading to dangerously high levels circulating around the body.

The study found that in men who smoked, the risk of developing diabetes was almost twice as high as in men who had never smoked. Even more alarming was that men who smoked at least 31 cigarettes a day were more than four times more likely to get diabetes. In men who used to smoke but gave it up, the risk of diabetes was the same as for people who had never smoked, but their bodies did appear to have some difficulty handling sugar levels.

No one knows why smoking should produce these results, the authors write. Other studies have shown that cigarette smoke can temporarily raise blood sugar levels, and can affect the activity of insulin. But how cigarettes actually do this remains to be determined. "All we can say is that smokers had a higher risk of diabetes," Saudek says. "We can't be certain that smoking was actually the cause."

"Smoking has profound metabolic effects," says endocrinologist Joseph Prendergast, MD. "No one has looked at this in the detail it warrants." Prendergast, an associate clinical professor of medicine at the University of California, San Francisco, reviewed the study for WebMD.

Like Saudek, he warns that it is premature to conclude that smoking causes diabetes. "Japan is becoming McDonaldized," he says. "[Smoking] is perhaps only one of a lot of little things [that may be contributing to an increased diabetes risk]."

"The interesting thing here is that this group of middle-aged Japanese men were at higher risk of developing diabetes," Saudek says. "I think it's an important finding, and is another reason for people at risk of diabetes not to smoke."

For more information from WebMD, see our Diseases and Conditions page on Smoking Cessation.