• Arsenic Exposure Could Increase Diabetes Risk
• Cognitive Problems Associated With Diabetes Duration and Severity

Arsenic Exposure Could Increase Diabetes Risk

Inorganic arsenic, commonly found in ground water in certain areas, may increase the risk of developing type 2 diabetes, according to a study by researchers at the Johns Hopkins Bloomberg School of Public Health. The study found that individuals with diabetes had higher levels of arsenic in the urine compared to individuals without diabetes. The results were published in the Jouranl of the American Medical Association.

“Our findings suggest that low levels of exposure to inorganic arsenic may play a role in diabetes,” Ana Navas-Acien, MD, PhD, lead author of the study and assistant professor with the Bloomberg School’s Department of Environmental Health Sciences said. “While prospective studies are needed to establish whether this association is causal, these findings add to the existing concerns about the long-term health consequences of low and moderate exposure to inorganic arsenic.”

Inorganic arsenic is found naturally in rocks and soils. In the U.S., most exposure to inorganic arsenic comes from contaminated drinking water. Foods such as flour and rice can also provide small quantities of inorganic arsenic, particularly if grown or cooked in areas with arsenic contamination in soil or water. Seafood is a source of organic arsenic compounds that have little or no toxicity.

Researchers examined randomly selected urine samples taken from 788 U.S. adults 20 years or older that participated in a 2003-2004 National Health and Nutrition Examination Survey. The results were adjusted for diabetes risk factors, including body mass index and for organic arsenic compounds found in seafood.

In the U.S., approximately 13 million people live in areas where the concentration of inorganic arsenic in the public water supply exceeds standards established by the U.S. Environmental Protection Agency, primarily in the West, Midwest and Northeast regions. Dietary intake of inorganic arsenic in the U.S. ranges from 8.4 to 14 micrograms per day for various age groups.

The authors concluded that given widespread exposure to inorganic arsenic from drinking water worldwide, clarifying the contribution of arsenic to the diabetes epidemic is a public health research priority with potential implications for the prevention and control of diabetes.

Cognitive Problems Associated With Diabetes Duration and Severity

Individuals with mild cognitive impairment appear more likely to have earlier onset, longer duration and greater severity of diabetes, according to a report in the August issue of Archives of Neurology.

Mild cognitive impairment is a transitional stage between normal aging and dementia, according to background information in the article. Previous studies have found an association between mild cognitive impairment and diabetes. Poor blood glucose control over time may lead to neuron loss, and diabetes is associated with cardiovascular disease risk and stroke, which also may increase the risk of cognitive impairment.

Rosebud O. Roberts, MB, ChB, MS, and colleagues at Mayo Clinic, Rochester, Minn., studied individuals from Olmsted County, Minn., who were age 70 to 89 on Oct. 1, 2004. Participants received a neurological examination, neuropsychological evaluation and tests of blood glucose levels, and completed an interview with questions about diabetes history, treatment and complications. Medical records linkage system was used to confirm diabetes history.

Rates of diabetes were similar among 329 individuals with mild cognitive impairment (20.1%) and 1,640 participants without mild cognitive impairment (17.7%). However, mild cognitive impairment was associated with developing diabetes before age 65, having diabetes for 10 years or longer, being treated with insulin and having diabetes complications.

“Severe diabetes mellitus is more likely to be associated with chronic hyperglycemia [high blood glucose], which, in turn, increases the likelihood of cerebral microvascular disease and may contribute to neuronal damage, brain atrophy and cognitive impairment,” the authors wrote.

Individuals with the eye disease diabetic retinopathy were twice as likely to have mild cognitive impairment supports the theory that diabetes-related damage to blood vessels in the brain may contribute to the development of cognitive problems.

“Our findings suggest that diabetes mellitus duration and severity, as measured by type of treatment and the presence of diabetes mellitus complications, may be important in the pathogenesis of cognitive impairment in subjects with diabetes mellitus,” they conclude. “In contrast, late onset of diabetes mellitus, short duration of diabetes mellitus or well-controlled diabetes mellitus may have a lesser effect.”