People with higher levels of pesticides and other pollutants in their blood may be more likely to get type 2 diabetes, suggests a new study of elderly Swedes.
The findings add to a growing body of evidence that these chemicals might drive changes in the body that lead to diabetes, researchers say, although they don't prove that one causes the other.
Taken together, the data suggest that there's more to the diabetes than eating too much and not getting enough exercise, said Dr David Carpenter, head of the Institute for Health and the Environment at the University at Albany in New York.
The pollutants, including pesticides and poly-chlorinated biphenyls, or PCBs, are largely found in meat and fatty fish. Some of them, including PCBs –once used in paint, plastics, and for electrical equipment manufacturing are heavily regulated and no longer used in many countries.
However, "the exposure to these chemicals in the general population still occurs because they have widely contaminated our food chain," study researcher Dr Duk-Hee Lee, of Kyungpook National University in Daegu, South Korea, said.
In the current study, Dr Lee and colleagues sought to follow up on previous findings that had linked these chemicals with type 2 diabetes.
They recruited a group of 725 diabetes-free elderly adults in Sweden and took blood samples to measure their levels of the pollutants. Then, the researchers followed them for the next five years.
Thirty-six of the study participants were diagnosed with type 2 diabetes over that time. When Dr Lee's team accounted for other diabetes risks such as weight, exercise, and smoking, people who had high levels of PCBs were up to nine times more likely to get diabetes than those with very low pollutant levels in their blood.
The link was smaller for some pesticides, while others weren't linked to diabetes at all, according to the findings, which are published in Diabetes Care.
The authors note that the number of new diabetes cases was low, and the findings can't prove that PCBs or other pollutants cause diabetes.
But research suggesting that's the case is piling up, said Dr Carpenter, who wasn't involved in the new study.
More than 8% of the US population has diabetes, according to the National Institutes of Health - most of them type 2 diabetes. The authors speculate that long-term exposure to environmental pollutants could affect pancreatic islet cells.
It would make sense that heavier people are more at risk of diabetes, Dr Carpenter added, because they're also probably eating more fatty meat and fish high in these chemicals –and they have more fat themselves where these chemicals are stored.
(Reuters Health, Genevra Pittman, June 2011)