The results of two studies published in Diabetes Care, one in 20061, and one in 20072, both led by Dr. Duk-Hee Lee, reveal a significant association between environmental pesticides and type 2 diabetes.The first study was a cross sectional analysis involving 2,016 adult participants from the National Health and Nutrition Examination Survey of 1999–2000. It examined the relationship between toxic persistent organic pollutants (POPs) and diabetes.
After adjusting for age, sex, race/ethnicity, poverty income ratio, BMI, and waist circumference, the odds ratios (ORs) were 1.0, 16.9, 15.8, 36.7, and 38.0 (P for trend < 0.001), for five categories of exposure. That means there was a 38-fold greater odds of having diabetes for those in the highest exposure group compared to those in the lowest exposure group.*
Another interesting finding of this study was that being obese was not associated with having diabetes if the subject's blood levels of POPs were low. So, being thin but having high levels of POPs could place you at greater risk for diabetes than being overweight but having low levels.
* This study cited the source of many of these toxins: "Greater than 90% of POPs comes from animal foods in the general population without occupational or accidental exposures."
The second study was a cross-sectional analysis involving 749 nondiabetic adults. It examined the relationship between POPs and insulin resistance.
The adjusted odds ratios were 1.8 for being equal to or above the 50th percentile for insulin resistance, 4.4 for the 75th percentile, and 7.5 for the 90th percentile. So, there was almost an 8-fold greater odds of having insulin resistance for those in the highest exposure group than the lowest.
The strongest associations were found for organochlorine (OC) pesticides or nondioxin-like polychlorinated biphenyls (PCBs).
An interesting finding of this study was that the association between OC pesticides and insulin resistance strengthened as waist circumference increased, suggesting that POPs may interact with obesity to increase the risk of type 2 diabetes.
Finally, a commentary that appeared in the January 26th edition of The Lancet3 drew attention to Dr. Lee's findings:
"This result was a surprise for many people working in diabetes research, because most studies to date have focused on the effects of genetics and the westernisation of dietary habits and lifestyle, while ignoring the potential effect of xenobiotics."And note that:
"... an increasing number of reports suggest that chronic dietary exposure to, and accumulation of, low concentrations of environmental pollutants within the body might also be associated with diabetogenesis."
1 A Strong Dose-Response Relation Between Serum Concentrations of Persistent Organic Pollutants and Diabetes
2 Association Between Serum Concentrations of Persistent Organic Pollutants and Insulin Resistance Among Nondiabetic Adults
3 Environmental Pollution And Diabetes: A Neglected Association, The Lancet, Vol. 371, No. 9609, 26 January 2008.
