MONDAY, Sept. 28, 2009 (HealthDay News) -- Women with type 2 diabetes have a 26 percent increased risk of developing atrial fibrillation, a potentially life-threatening irregular heartbeat, new findings suggest.
The overall incidence of atrial fibrillation was 3.6 percent among people with type 2 diabetes, while the rate for people without the metabolic condition was only 2.5 percent, according to the study, which will be published in the October issue of Diabetes Care.
"We found that people with diabetes have about a 44 percent higher prevalence of atrial fibrillation," said study author Gregory Nichols, an investigator at Kaiser Permanente Center for Health Research in Portland, Ore. "When we stratified the data by sex, the association was still elevated for men -- but not statistically significant -- but for women, it was still statistically significant."
The researchers were not able to tease out from the data in this study why women with diabetes might have a higher rate of atrial fibrillation. The authors theorize that diabetes may affect the cardiac autonomic nerves in much the same way the disease damages peripheral nerves and causes a condition known as peripheral neuropathy.
Not everyone is convinced that cardiac neuropathy is to blame, however. "In people with diabetes, the cluster of other cardiac risk factors, like obesity and hypertension, increases the risk of atrial fibrillation," said Dr. Howard Weintraub, clinical director of the Center for the Prevention of Cardiovascular Disease at the NYU Langone Medical Center in New York City.
Diabetes is a known risk factor for heart disease. As many as 65 percent of people with diabetes will die from heart disease and stroke, according to the American Diabetes Association. Death rates from heart disease are up to four times higher for people with diabetes when compared to people without diabetes.
The current study culled data from more than 10,000 members of an HMO diabetes registry who had type 2 diabetes, and then matched them by age and sex to more than 7,000 people without diabetes. The study period was January 1999 through December 2008.
Over an average follow-up time of about seven years, people with type 2 diabetes developed 9.1 cases of atrial fibrillation per 1,000 person-years, according to the study. During the same period, there were 6.6 cases (per 1,000 person-years) of atrial fibrillation in people without diabetes.
When the researchers adjusted the data to account for other factors, such as obesity and high blood pressure, they found that the increased risk of atrial fibrillation in people with type 2 diabetes only remained for women.
Nichols said that this information is important for doctors to know because they might not always look for atrial fibrillation in women.
But, he added, in this study, "among women, diabetes was a stronger predictor of atrial fibrillation than obesity and elevated blood pressure."
Weintraub pointed out that this study didn't include comparisons of echocardiograms (an imaging test of the heart), which would have allowed researchers to assess heart health at the start of the study, and ensure that no one with preexisting, but undiagnosed, heart disease was included. Additionally, the researchers didn't look to see if blood sugar control made a difference in the rates of atrial fibrillation.
"Diabetes is a metabolic disorder in which heart disease risk factors cluster," said Weintraub. He added that one important take-away message from this study is to try to aggressively control your weight and blood pressure levels, particularly if you have diabetes, because it increases your risk of atrial fibrillation and other forms of heart disease.
For more on heart disease and diabetes, as well as tips for improving your cardiovascular health, visit the American Diabetes Association.