Air Pollution Could Cause Problems for Diabetics
Persons with diabetes may be at higher risk for cardiovascular problems when air pollution levels are higher, according to a new study published in the medical journal Circulation.
Diabetes is a metabolic disorder characterized by a failure to secrete enough insulin, or, in some cases, the cells do not respond appropriately to the insulin that is produced. Because insulin is needed by the body to convert glucose into energy, these failures result in abnormally high levels of glucose accumulating in the blood.
Diabetes is widely recognized as one of the leading causes of death and disability in the US, affecting more than 13 million Americans.
A study of Boston-area residents found that the ability of the blood vessels to control blood flow was impaired in adults with diabetes on days with elevated levels of particles from traffic and coal-burning power plants.
The researchers evaluated several kinds of fine particles found in urban air pollution. These included sulfate particles, which come mainly from coal-burning power plants, as well as ultra-fine particles and black carbon soot, which are generated primarily by diesel- and gasoline-powered vehicles.
“Our strongest finding was that blood vessel reactivity was impaired in people with diabetes on days when concentrations of sulfate particles and black carbon were higher,” says Marie O’Neill, Ph.D., an epidemiologist at the Robert Wood Johnson Health and Society Scholars program at the University of Michigan.
“Impaired vascular reactivity has been associated with an increased risk of heart attack, stroke, and other heart problems,” says Dr. O'Neill, lead author on the study.
“Previous studies have shown that when air pollution levels are higher, people with diabetes have higher rates of hospitalization and death related to cardiovascular problems,” says Dr. David Schwartz, director of the National Institute of Environmental Health Sciences.
“These changes in blood vessel reactivity may help explain this phenomenon,” he says.
“We don’t really understand why fine particles may cause this decrease in vascular reactivity,” says Dr. O’Neill. “Further research is needed to confirm this association between air pollution and vascular health and to understand what causes people with diabetes to be especially sensitive.”
Researchers recruited 270 greater Boston metropolitan residents and divided them into two groups.
The first group consisted of persons with a positive diagnosis of type I or type II diabetes. The second group included individuals who were not diabetic, but who had a family history of diabetes or blood sugar levels slightly higher than normal.
The investigators used a technique called brachial artery ultrasound to assess blood vessel response in the study subjects.
The measurement was obtained by applying a pressure cuff to the persons upper arm and cutting off the blood flow through the arm’s main artery. Researchers then released the cuff, allowing the blood to rush through.
The researchers then evaluated changes in the diameter of the main artery as a result of the physical stress placed on the vessel.
“We observed an 11 percent decrease in diabetics’ vascular reactivity on days when sulfate particle concentrations were higher than normal,” remarks Dr. O’Neill. “We also noted a 13 percent decrease in their vascular reactivity on days with higher-than-normal black carbon concentrations.
“We hope our study will remind people that reducing air pollution is important for everyone’s health, but especially for vulnerable members of our population, including the elderly and people with chronic health problems such as diabetes,” she says.
Always consult your physician for more information.
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Men age 45 and older with diabetes may be more than twice as likely as non-diabetic men to have low testosterone levels, researchers report at the American Diabetes Association annual meeting in San Diego.
The multi-center study, involving more than 2,100 men in 26 states, also found that sexual dysfunction was the most common symptom experienced by men with diabetes and low testosterone.
"In our study, more than half the men with diabetes also had low testosterone levels suggesting a higher prevalence of [low testosterone] among diabetic men than previously reported," says study co-investigator Dr. Sherwyn L. Schwartz, director of the Diabetes and Glandular Disease Clinic in San Antonio.
The study found that 38.7 percent of the 2,162 men had low testosterone and 23 percent had a history of diabetes.
The majority of men with low testosterone were not receiving testosterone treatment.
Of the 474 men who had a history of diabetes and were not receiving testosterone treatment, 237 (50 percent) had low levels of the hormone.
Using these figures, the researchers calculated that men age 45 and older with diabetes have double the risk of low testosterone than men without diabetes.
An estimated 13 million American men age 45 and older have low testosterone, but fewer than 10 percent are receiving treatment, the study authors note.
Signs and symptoms of low testosterone include diminished interest in sex, erectile dysfunction, decreased bone mineral density, reduced muscle mass and strength, increased fat mass, and depressed mood and fatigue, according to the San Antonio team.
Men with chronic conditions such as diabetes, hypertension, obesity, asthma, and hyperlipidemia (elevated levels of lipids, or fats, in the blood) are more likely to have low testosterone than other men, the researchers say.
Another expert notes that lowered testosterone is a normal function of age, and debate continues within the field as to whether most older men will benefit from hormone replacement therapies.
Dr. Shalender Bhasin, chief of the division of endocrinology at Charles R. Drew University in Los Angeles, and a professor of medicine at UCLA School of Medicine, says "There's also no question that testosterone levels decline with advancing age.
"But are the [physical] declines seen in older men related to declining testosterone levels? On that point there's no agreement," Dr. Bhasin says.
The study was funded by Solvay Pharmaceuticals, Inc., which makes testosterone-replacement therapy.
Always consult your physician for more information.
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