Persistent organic pollutant exposure linked to diabetes risk
(27 February 2007: VIDYYA MEDICAL NEWS SERVICE) -- People with high levels of persistent organic pollutants (POPs) in their blood are more likely to develop insulin resistance, a precursor for type 2 diabetes, according to a study by researchers in Korea.
Previous research by the same group found a link between POPs and type 2 diabetes. This study confirms that background exposure to some POPs, chemicals such as organochlorine pesticides and polychlorinated biphenyls (PCBs), is also associated with insulin resistance among people who do not yet have diabetes.
The researchers also found that the association between organochlorine pesticides and insulin resistance became stronger as people got fatter. However, among people who had very low concentrations of pesticides in their blood, the researchers found little association between waist size and insulin resistance.
Some studies have suggested an association between background exposure to POPs and a variety of adverse health effects in humans and wildlife. POPs can be particularly problematic because they persist for long periods of time in the environment, accumulate up the food chain, and can travel great distances through the air and water. Therefore, even people and animals that live nowhere near a place where POPs are being applied often show high levels of these chemicals in their bloodstream.
An international treaty banning a dozen of the world's most dangerous POPs has helped reduce exposures, but many harmful chemicals remain in use and even those that have been banned may linger in our environment for years to come. For example, chlordane was banned two decades ago in the United States but continues to be present at high levels in our food supply.
The researchers concluded that some POPs "may be involved in the pathogenesis of insulin resistance." They advise urgent prospective studies among those who have background exposure to POPs, which mostly comes from eating fatty animal foods. Since obesity may increase the toxicity of POPs, controlling weight could also help to reduce these impacts.
Panel Agrees on Whom to Test, How to Treat Pre-Diabetes
People who have pre-diabetes should undergo intensive lifestyle interventions, and possibly drug therapy, to reduce their risk of developing diabetes, as well as their long-term risk for developing diabetic complications, according to a consensus statement being published in the March issue of Diabetes Care.
A seven-member panel of experts convened by the American Diabetes Association last year developed these guidelines and others geared toward people who exhibit early metabolic abnormalities. The panel's report grew out of concerns arising from the growing epidemic of type 2 diabetes, which now affects more than 20 million Americans. The disease is expected to continue increasing dramatically worldwide over the next two decades.
Type 2 diabetes is frequently preceded by one of two conditions together thought of as "pre-diabetes." These conditions -- called impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) -- are similar in that they represent a state of abnormal glucose regulation that is not yet high enough for a diagnosis of diabetes but is too high to be considered normal. While these two states may affect different groups of people, both ultimately lead to type 2 diabetes in the majority of cases. However, previous studies, including the Diabetes Prevention Program, have demonstrated that lifestyle interventions aimed at weight reduction and increased physical activity, and medications, can substantially reduce the development of diabetes.
The panel convened over a three-day period in 2006 to answer questions such as how IFG and IGT differ; whether they should be treated (and how); and who should be screened for these conditions. The answers to these and other questions are included in the 7-page consensus statement.
The report's recommendations include:
-- Lifestyle interventions (losing 5-10 percent of body weight and
moderate intensity physical activity for at least 30 minutes per day)
for any person exhibiting IFG or IGT, to prevent/delay the onset of
diabetes and to help reduce the long-term risk of developing diabetic
-- Making weight loss and obesity prevention priorities in the United
States because of the strong association between obesity and type 2
diabetes. The panel advised intensive weight-loss counseling for those
who need it; changes in school-based meals and exercise programs;
community infrastructure changes that are conducive to frequent
exercise; and legislation that promotes a healthy lifestyle.
-- The use of metformin as optional drug therapy, limited to those with
both IFG and IGT who also have one or more additional high risk
factors, because it has been shown to be most effective for these
-- Screening for IFG/IGT for anyone who is at risk for diabetes.
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