New Guidelines Urge A1C Test for Diabetes Diagnosis

TUESDAY Dec. 29, 2009 -- In its latest set of clinical guidelines, the American Diabetes Association is promoting a more prominent role for the hemoglobin A1C blood test in the diagnosis of type 2 diabetes and prediabetes.

Long used in the management of diabetes, the A1C blood test measures average blood sugar levels for the previous two to three months. The new guidelines call for the diagnosis of type 2 diabetes at A1C levels above 6.5 percent, and prediabetes if the A1C levels are between 5.7 and 6.4 percent.

"We've added another test that can make it easier to find out if you have diabetes," said Dr. Richard Bergenstal, president-elect of medicine and science for the American Diabetes Association (ADA).

The new guidelines will be published in the January issue of Diabetes Care.

Bergenstal said the A1C isn't necessarily superior to other methods used to detect type 2 diabetes and prediabetes, such as fasting blood sugar tests and the oral glucose tolerance test, but it is easier and more convenient for people because you don't have to fast before an A1C test.

In the past, the A1C wasn't recommended for use in the diagnosis of diabetes because the test wasn't standardized from lab to lab, according to the ADA. That means a reading of 6.5 percent at one lab could have been 6.3 percent at another. Now, the test is highly standardized, according to the ADA, making it a useful tool for detecting diabetes and prediabetes without the need for fasting.

"I think we may diagnose more people because the A1C is used a lot more now because of its convenience," Bergenstal said.

The A1C measures the percentage of hemoglobin (the main component of red blood cells) in the blood that is glycated. Glycated hemoglobin is hemoglobin that has a blood sugar molecule attached to it, which happens when blood sugar levels are higher than they should be.

Generally, people without diabetes have an A1C level of less than 5 percent.

This percentage gives the doctor an idea of what the patient's blood sugar levels have been for the past two to three months, which may help diagnose more people with type 2 diabetes and prediabetes sooner than they might have been in the past.

"This is a very practical, innovative concept," said Dr. Michael Bergman, an endocrinologist and a clinical associate professor at the NYU Langone Medical Center in New York City. "People don't need to be fasting for an A1C, and there are fewer variables that can affect the outcome of the A1C," he explained.

"I think diabetes is grossly underdiagnosed and prediabetes, even more so. It's a real problem, and these guidelines may help sensitize the medical community to it," said Bergman.

Bergenstal said the ADA does recommend that A1C levels should be measured using a central lab, rather than a point-of-care A1C test. Like blood glucose monitors, some doctors' offices have A1C tests that can provide nearly instant A1C test results. And, while these machines can be useful in the management of diabetes, the ADA is not recommending that they be used for the initial diagnosis of diabetes or prediabetes.

More information

Learn more about the hemoglobin A1C test from the U.S. National Library of Medicine.

Posted: December 2009


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