Wednesday, January 6, 2010

Quitting Smoking Increases Diabetes Risk

Smoking is an established risk factor for type II (adult onset) diabetes. A new study, published this week in the Annals of Internal Medicine, found that the diabetes risk from quitting smoking is even higher.

A group of researchers from The Johns Hopkins University evaluated the development of diabetes among participants of the Atherosclerosis Risk in Communities (ARIC) Study, which has followed 16,000 middle-aged adults from Forsyth County, North Carolina; Jackson, Mississippi; Minneapolis; and Washington County, Maryland. Using never smokers as the referent comparison group, the investigators assessed the risk of developing diabetes among former smokers (who had quit before entering the study), new quitters (who quit after study enrollment), and continuing smokers.

Compared with never smokers, the risk for diabetes among continuing smokers was 1.3 (95% CI = 1.0-1.7), a 30% increase (only a modest elevation in real-world terms). This is consistent with previous studies, and it is unsurprising since smoking is associated with many diseases.

The unexpected finding was the elevated risk among smokers who had quit. Normally, a smoker can expect a reduction in risk for illnesses after quitting. The decline in risk comes quickly for some diseases, such as heart attacks, while it falls more gradually for lung and other cancers. But the diabetes risk for new quitters in this study was 1.7 (CI = 1.2-2.5), which is twice the risk among smokers.

Does this make sense? Absolutely. Numerous studies have documented that cigarette smoking suppresses body weight, and that quitting is commonly followed by substantial weight gain. The weight gain ranges from 6 to over 20 pounds, and it is dreaded by smokers as much as it is ignored by anti-tobacco activists. This study shows that it is a significant risk factor for diabetes.

I have conducted research with Swedish collaborators on tobacco use and its effect on weight and diabetes. In 2004, I was the lead author of a study documenting that Swedish men who quit smoking by switching to snus avoid weight gain.

We conducted a study using World Health Organization data from northern Sweden. Smokers who quit tobacco entirely gained significantly more weight (about 1% per year) than smokers who switched to snus (about half a percent), nonusers (annual 0.4% gain) or continuing snus users (0.4%).

Also in 2004, I was the senior author of a study of the effect of smoking and snus use on type II diabetes. We found that, compared with nonusers, the risk of developing clinically diagnosed diabetes during follow-up was 4.63 ( CI = 1.37-16) in smokers and 3.20 (CI = 1.16-8.8) in ex-smokers. Importantly, we found NO cases of diabetes in snus users.

Smoking cessation was estimated to be responsible for about one quarter of the increase in prevalence of overweight among men in the U.S. during the 1980s. Because modern smokeless tobacco products deliver nicotine in satisfying doses that permit smokers to quit without gaining weight, they may prevent the development of type II diabetes that is prevalent in smokers who quit by abstaining completely from tobacco.

Smokers: gain less weight and lower your risk for type II diabetes by switching to smokeless.

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