In one study, Dr. Sherita Golden and colleagues at Johns Hopkins University in Baltimore reanalyzed the data from 13 studies involving nearly 10,000 people from North America and Europe and found those with higher levels had much higher risks of heart and artery disease.

Writing in the Annals of Internal Medicine, they said a 1-percent increase in HA1c predicted an 1-percent increase in risk for total cardiovascular disease and a 28-percent risk for peripheral vascular disease -- clogged arteries in the legs, for instance.
Although diabetes is known to double the risk of heart disease death, Golden said the specific relationship is unclear. "As a result, many people living with diabetes monitor their health for well-known risk factors for heart disease, such as obesity, cholesterol levels and blood pressure, but the big unknown has been the role of blood sugar levels in managing their risk of developing cardiovascular disease," she said in a statement.

A second study found similar results.

Dr. Kay-Tee Khaw of Cambridge University and colleagues at Britain's Medical Research Council studied 10,030 people, between 45 to 79 years old, for six years.
They found a 21-percent increase in cardiovascular "events" such as heart attack, for every 1 percent increase in hemoglobin A1c above 5 percent.
"Persons with HA1c concentrations less than 5 percent had the lowest rates of cardiovascular disease and mortality," they wrote.
This was true even when patients were older and fatter and regardless of blood pressure or cholesterol levels.

The two studies "clearly prove that the glycosylated hemoglobin level is an independent progressive risk factor for incident cardiovascular events, regardless of diabetes status" Dr. Hertzel Gerstein of McMaster University in Ontario, Canada wrote in a commentary.
"Glycosylated hemoglobin level can now be added to the list of other clearly established indicators of cardiovascular risk, such as blood pressure and cholesterol level," added Gerstein, a diabetes expert.

Dr. Hertzel C. Gerstein, who wrote an editorial accompanying the studies, said that when people are having tests to assess their risk for heart disease, their A1c should be measured. The test is now used mostly to monitor treatment in people who have diabetes, and not in others. It is not used to diagnose diabetes, because it can miss early cases. But the A1c test should be used more often to gauge a patient's heart disease risk, he said.

Dr. Nathaniel G. Clark, national vice president for clinical affairs of the American Diabetes Association, said the idea of using A1c to help determine cardiovascular risk was "a very interesting suggestion," and the test "may go into this category of tests we don't now do, but should."

Source: Diabetes In Control.com.