Cigarette smoke is tied to a higher risk of type 2 diabetes, both for smokers and the people around them, a new study shows.
The more secondhand smoke people are exposed to, the greater their risk of type 2 diabetes, according to the paper published online 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 Centre 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, said Nathan, who was not involved in the study.
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 participating in the Nurses Health Study 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.
Dr 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 second-hand 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% higher risk of diabetes compared to women who were regularly exposed to secondhand smoke.
In this study, nearly all the women were white, but "there's no a priori reason to think that this wouldn't apply to men as well," Dr Nathan said.
He said no one knows why smoking and type 2 diabetes are linked, but inflammation may play a role in both.
But "did we need another reason not to smoke? I don't think so," he said.
(Reuters Health, Leigh Krietsch Boerner, March 2011)