Swiss-Canadian study: Strong evidence for type 2 diabetes from smoking

William Atkins
Sunday, 20 January 2008 15:09

Science - Health

A study conducted by researchers from Switzerland and Canada looked at the results of twenty-five other studies and concluded there is “strong evidence” that active smoking causes type 2 diabetes.        

Carole Willi (from the Ambulatory Care and Community Medicine, and Institute of Social and Preventive Medicine, University of Lausanne, Switzerland) led the research study that looked at the conclusions of twenty-five other studies involving about 1.2 million subjects.

Their data came from MEDLINE (1966 to May 2007), EMBASE (1980 to May 2007), and various articles, abstracts, and experts.

The Willi team of researchers looked for impaired fasting glucose, impaired glucose tolerance, and other such ailments, along with the presence or absence of a history of actively smoking. Two researchers independently looked at each set of data.

After studying these results, the Willi team concluded, “Active smoking is associated with an increased risk of type 2 diabetes.” Specifically, they found that smoking at least one pack of cigarettes every day raises the risk of developing type 2 diabetes by as much as 61 percent. [JAMA]

For smokers that smoke less than one pack per day, their increased risk of getting type 2 diabetes is about 29 percent over people who have never smoked.

The researchers also state that former smokers had a 23 percent increased chance of getting type 2 diabetes over non-smokers/never-before-smokers.

Their study (“Active Smoking and the Risk of Type 2 Diabetes: A Systematic Review and Meta-analysis”) was written up in the December 12, 2007 issue of the Journal of the American Medical Association (JAMA, 2007: 298(22):2654-2664).

From the article “Smoking ups risk for type 2 diabetes” in Science News magazine (January 12, 2008), the authors caution that their results “cannot conclusively prove that smoking causes diabetes” only that “there is strong evidence that it does.”

This strong evidence comes in the form of three major findings: (1) smoking was found to come before type 2 diabetes in all cases within the studies, (2) smoking over the long-term led to higher risks for type 2 diabetes, and (3) studies outside of this study also found a biological relationship between smoking and type 2 diabetes.

Willi’s team includes Patrick Bodenmann and Jacques Cornuz from the University of Lausanne, Switzerland, and William A. Ghali and Peter D. Faris from the University of Calgary (Canada).
Willi will conduct additional research to establish the cause and effect of this association between active smoking and type 2 diabetes and to establish ways to show how this relationship originates.