Secondhand Smoke Raises Diabetes Risk

Cigarette smoke is tied to a higher risk of Type 2 diabetes, both for smokers and the people around them, a new study shows.

And the more secondhand smoke people are exposed to, the greater their risk of Type 2 diabetes, according to the paper in Diabetes Care.

The potential risks of diabetes from being exposed to secondhand smoke weren't previously known, said Dr. David Nathan, who heads the Diabetes Center at Massachusetts General Hospital and is a professor at Harvard Medical School.

"This just reinforces the lesson from a public health point of view that we've been stressing for decades," which is to limit exposure to cigarette smoke, Nathan, who was not involved in the study, told Reuters Health.

For the new research, Dr. John P. Forman at Brigham and Women's Hospital in Boston and colleagues looked at the responses of more than 100,000 women to questionnaires they had answered in 1982. The women — all nurses participating in a national study that would last several decades — provided information about how much time they spent around cigarette smoke.

During the next 24 years, about one in 18 women were diagnosed with Type 2 diabetes.

Overall, about one in 13 people in the United States have this disease, according to the National Institutes of Health. Type 2 diabetes, in which the body can't process sugar properly, usually develops in adults. Sometimes it can be controlled by diet and exercise, but advanced cases require insulin treatment and can have life-threatening complications.

Forman's group found that women who smoked more than two packs a day had the highest odds of developing diabetes. For every 10,000 women in the study, about 30 of the heavy smokers got diabetes every year, compared to about 25 women who didn't smoke and didn't spend time exposed to other people's cigarette smoker.

The risks were actually higher for ex-smokers and for women exposed to secondhand smoke. In both of these groups, about 39 of every 10,000 women developed diabetes each year. However, once the researchers took things such as weight status, age, and family history of diabetes into account, the ex-smokers had a 12 percent higher risk of diabetes compared to women who were regularly exposed to secondhand smoke.

Even though the smokers had a lower risk of developing diabetes in this study, that doesn't mean it's better for them to continue smoking, Nathan said.

In this study, nearly all the participants were white women, but Type 2 diabetes affects men and women fairly equally, Nathan said.

"There's no (prior) reason to think that this wouldn't apply to men as well," he told Reuters Health, since the risk factors for the disease are the same for both sexes.

Nathan said no one knows why smoking and Type 2 diabetes are linked, but inflammation may play a role in both.

Forman and his team did not respond to requests for comment by deadline.

Nathan noted that the study can't prove that smoking causes diabetes. It just shows they are associated with each other.

But "did we need another reason not to smoke? I don't think so," he said.