Experts: A1c testing could help detect undiagnosed diabetes

A blood test more often used to monitor the progress of diabetes should be considered as a screening and diagnostic tool to reduce the number of people who have the disease and don't know it, according to an expert panel convened to consider the question. The statement was published by the Journal of Clinical Endocrinology & Metabolism online May 6 and will appear in the July print edition.

"There are serious deficiencies in the current criteria for diagnosing diabetes, and these shortcomings are contributing to avoidable morbidity and mortality," said Christopher Saudek, MD, lead author and professor of endocrinology and metabolism at Johns Hopkins School of Medicine in Baltimore.

According to the Centers for Disease Control and Prevention, 6.2 million people have diabetes but have yet to be diagnosed. The paper advocates using A1c testing to reduce these numbers because, unlike other screening tools, it does not require fasting -- a usual testing prerequisite many consider an impediment to increased detection.

Those behind this article suggest that A1c would be useful particularly for those with minimal access to health care, because it could be carried out when they receive sick care without having them return the next day.

"A number of people don't have regular health care at all, and they have diabetes and they don't know it. They show up with a cough or sore throat or even for an emergency room visit," said David Edelman, MD, one of the authors and associate professor of internal medicine at Duke University in Durham, N.C. "It's that population that we are trying to reach."

The proposal has received some support. Some physicians already are using A1c as a diagnostic in opposition to American Diabetes Assn. guidelines, although the question is under consideration by the ADA and others. Future guidelines may state otherwise.

"The average patient who shows up to the doctor is not fasting, and having to come back for a second visit is a barrier," said John Buse, MD, PhD, the ADA's president for medicine and science and a member of the organization's Expert Committee on the Diagnosis and Classification of Diabetes Mellitus.

But while there is support, controversy also abounds. Experts expressed concern about the greater cost associated with A1c testing compared with more widely accepted blood glucose measuring.

Also, while A1c is a very specific test, it's not very sensitive. These numbers can be normal in the early stages of the disease, which could lead to people being incorrectly reassured that they don't have diabetes when they actually do.

"We are much more likely to miss people with diabetes, and people could get a false sense of security," said James Mulinda, MD, a staff endocrinologist with Carilion Clinic in Roanoke, Va.

Many also questioned how big a barrier the need to fast actually is and argued that assessment of A1c may be appropriate for a select group of patients who are unable or unwilling to fast. Glucose measurement, however, should still be the first choice.

"It really depends on what your patients are like," said Tae Joon Lee, MD, assistant clinical professor in the Dept. of Family Medicine at Brody School of Medicine at East Carolina University in Greenville, N.C. "If they cannot or refuse to come in fasting, I think this is an acceptable alternative, but I think a lot who are undiagnosed don't even see a doctor. A lot may never come in for any kind of blood draw. This may not really solve the problem."

Those who were less than comfortable with more widespread use of A1c as a screening or diagnostic test also called for far more extensive study before it became a bigger part of medical practice.

Metrika Inc., a manufacturer of A1c testing equipment, funded the development of this consensus document, although panel meetings and manuscript preparation were independent of each other.