Type 2 Diabetes May be Linked to
CAMBRIDGE, UK, January 25, 2008 (ENS) - Cambridge
University scientists are advocating more research into the
possible links between environmental pollution and type 2
diabetes, the most common form of the disease. At least 171
million people worldwide suffer from diabetes, according to
estimates by the World Health Organization.
In today's edition of the British medical journal
"Lancet," Drs. Oliver Jones and Julian Griffin highlight the
need to research the possible link between persistent
organic pollutants, POPs, and insulin resistance, which can
lead to adult onset diabetes.
POPs is a group of chemicals which includes many
pesticides such as dieldrin, DDT, toxaphene and chlordane
and several industrial chemical products or byproducts
including polychlorinated biphenyls, or PCBs, dioxins and
In their commentary, Jones and Griffin cite peer reviewed
research which demonstrates a strong relationship between
the levels of POPs in blood, particularly organochlorine
compounds, and the risk of type 2 diabetes.
"Of course correlation does not automatically imply
causation," says Dr. Jones. “But if there is indeed a link,
the health implications could be tremendous."
"At present there is very limited information," he said.
"Research into adult onset diabetes currently focuses on
genetics and obesity; there has been almost no consideration
for the possible influence of environmental factors such as
Pesticide is sprayed on vegetables (Photo
courtesy Department of Environmental and Molecular
People with high levels of 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 that
is cited by Jones and Griffin.
Previous research by the same group found a link between
POPs and type 2 diabetes. This study confirms that
background exposure to chemicals such as organochlorine
pesticides and PCBs is also associated with insulin
resistance among people who do not yet have diabetes.
The Korean scientists found that people were more at risk
of diabetes if they were thin with high levels of POPs in
their blood than if they were overweight but with low levels
Dr. Jones said, "I think research should be carried out
to first test the hypothesis that POPs exposure can cause
diabetes, perhaps using cell or tissue cultures, so we know
for sure if this can occur."
"Assuming POPs can have this effect, the next step would
be to try and develop a method of treatment for those people
who might be affected," he said.
POPs came into prominence as effective pesticides with
the introduction of DDT in the 1940s. But many of these
chemicals, including DDT, fell out of favor after they were
blamed for the declining number of wild birds and other
animals and the possible negative human health effects.
The Stockholm Convention, an international treaty banning
a dozen of the world's most dangerous POPs that took effect
in May 2004 has helped reduce exposures, but many such
chemicals remain in use and even those that have been banned
may linger in the environment for years.
Once released, POPs can travel long distances in the
atmosphere before they are deposited on land or in water.
Humans can be exposed to POPs through diet, occupational
accidents and the environment.
As these compounds biodegrade slowly, they continue to
find their way into the food chain and ultimately into the
blood streams of individuals even though many of these
toxins were banned many years ago.
For example, chlordane was banned two decades ago in the
United States but continues to be present at high levels in
the U.S. food supply.
Because these compounds are fat soluble, they can persist
in body fat for very long periods of time following
It is well documented that significant exposure to POPs
can cause negative health effects. The U.S. Environmental
Protection Agency states that the pesticide chlordane, for
example, can cause cancer, can lead to behavioral disorders
in children if exposed before birth or while nursing, and
harms the endocrine system, nervous system, digestive
system, and liver.
But to date, the link between POPs and type 2 diabetes
has only been suggested, not confirmed.
Type 2 diabetes is the most common form of diabetes. In
type 2 diabetes, either the body does not produce enough of
the hormone insulin or the cells ignore the insulin.
Insulin is necessary for the body to be able to use
glucose for energy. When people eat, the body breaks down
sugars and starches in the food into glucose, the basic fuel
for the body's cells.
Insulin carries the glucose from the blood into the
cells. When glucose builds up in the blood instead of going
into cells, the cells may be starved for energy. Over time,
high blood glucose levels may damage the eyes, kidneys,
nerves or heart.
The article by Jones and Griffin, "Environmental
pollution and diabetes: A neglected relationship," appears
in today's edition of the "Lancet."