December 16, 2011

Can Pollution Cause Diabetes?

Traffic pollution raises type 2 diabetes risk slightly — especially in people who are healthier to begin with.

Of all the myriad variables that increase one’s risk for developing type 2 (adult onset) diabetes – smoking, being overweight, having a larger waistline – air pollution is not one we usually think of. But newer studies are suggesting environmental risk factors for diabetes: a new one finds that living in an area with more traffic pollution could increase one’s risk, particularly in people who are healthier to begin with.

In non-smokers who lived in high pollution areas, the risk for diabetes rose to 12%. A 10% increase in risk was found for physically active people.

Researchers followed 52,000 city-dwellers in Denmark over a period of ten years. During this time, about 2,800 participants (5.5%), who were 50-65 when the study started, developed diabetes. The researchers also measured nitrogen dioxide levels, as a marker of traffic pollution, around the homes of the participants.

The classic variables associated with diabetes were found in this study, as one would expect: advanced age, weight, smoking status, fat intake, blood pressure, cholesterol, and alcohol intake were all linked to greater risk of diabetes.

But beyond these variables, the researchers also found that living in areas with more pollution was correlated with an increased diabetes risk – but only slightly, at about 4%. The link was “borderline significant,” according to the researchers. It was, however, stronger for people who were in better overall health, and for women. For example, in non-smokers who lived in high pollution areas, the risk for diabetes rose to 12%. A 10% increase in risk was found for physically active people. Women were another group for whom traffic pollution appeared to have an especially large effect.

The reason for the connection may have to do with the fact that the chemicals in pollution could increase inflammation in the body, which is known to affect one’s risk for several conditions, including heart disease, stroke, and, of course, diabetes. This may be part of the reason that women were more sensitive to pollution than men: the authors reason that their bodies may handle inflammation differently from men (or, alternatively, they could spend more time around the home).

Healthier people may be more sensitive to the toxins from pollution precisely because they are healthy, and have fewer existing risk factors. But more research will be needed to flesh out the relationship between pollution, inflammation, and diabetes. Though environmental toxins may have a slight effect on one’s risk, it’s well demonstrated that lifestyle factors play an even bigger role in the development of diabetes. So making beneficial changes in your life – eating right, exercising, and not smoking – is likely the best way to reduce your risk.

The study was carried out by a team at the Danish Cancer Society and published in the journal, Diabetes Care.
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