Prior research has indicated that persistent organic pollutants (e.g., organochlorine pesticides; PCB's) may interfere with the body's ability to regulate blood sugar; some persistent organic pollutants have also been associated with obesity, itself a major risk factor for diabetes. Although many persistent organic pollutants have been banned, they (well) persist and are present in many humans.
Researchers measured blood levels of several persistent organic pollutants in about 2,000 older adults. Just over 15 percent had Type II diabetes; the risk was higher, the researchers found, among people with the highest levels of organochlorine pesticides. Those with levels in the top 10% were about twice as likely to have diabetes as their counterparts in the bottom 10%. But, the link appeared to be limited to people who were overweight or obese. As such, the researchers suggest that the being overweight or obese and the presence of persistent organic pollutants could be synergistic vis-a-vis Type II diabetes.
The researchers accounted for participants' age, sex, waist size, and blood pressure levels. However, they had no information on, among other things, diet and exercise habits, which might explain away the association. In support of their viewpoint, the researchers point out that persistent organic pollutants have been shown to be endocrine disruptors, which may support a causal relationship.
The report can be found at http://care.diabetesjournals.org/content/early/2011/07/26/dc10-2303.abstract.