A1c blood test can be additional diagnostic criterion for type 2 diabetes: American endocrinologists

A1c blood test has been approved as an additional diagnostic criterion for type 2 diabetes by the American Association of Clinical Endocrinologists (AACE).

A1C is a simple blood test and does not require fasting. It tests the level of glucose in hemoglobin A1C, the main fraction of glycosylated hemoglobin (glycohemoglobin).

Hemoglobin A1C is hemoglobin to which glucose is bound. (Hemoglobin, the substance in the red blood cells that carries oxygen to the cells of the body.) Since the glucose stays attached to hemoglobin for the life of the red blood cell (normally about 120 days), the level of hemoglobin A1C reflects the average blood glucose level over the past 4 months.

The level of hemoglobin A1C is increased in the red blood cells of persons with poorly controlled diabetes mellitus. Hemoglobin A1C is tested to monitor the long-term control of diabetes mellitus.

The normal level for hemoglobin A1C is less than 7%. Levels above 9% show poor control, and levels above 12% show very poor control. It is commonly recommended that hemoglobin A1C be measured every 3 to 6 months in diabetes.

An A1c of 6.5 or greater is now considered an alternate criterion for the diagnosis of type 2 diabetes.

The decision was announced in a position statement entitled “The AACE/ACE Statement on the Use of A1c for the Diagnosis of Diabetes,” by the American Association of Clinical Endocrinologists (AACE).

The position statement also reviews the limitations of A1C test. For example, certain ethnic groups may have marginally elevated values which do not necessarily indicate diabetes.

“Using A1c will provide doctors and patients a convenient additional tool to diagnose diabetes and thereby identify more patients with it,” said Dr. Jeffrey R Garber, president of AACE.

In December, the American Diabetes Association’s recommended A1C test as an easier and faster means of diagnosing diabetes and identifying pre-diabetes in new clinical practice guidelines.

The new recommendations, being published as a supplement to the January issue of Diabetes Care, also call for the addition of A1C test as a means to diagnose diabetes.
A1c is a test that is used to determine the average level of blood glucose over a prior three month period. It is currently used to measure glucose control in patients already diagnosed with diabetes. The test requires a single blood draw, and the results can be available the same day.

The most common criteria currently used to diagnose diabetes are a fasting glucose of 126 or greater or a 2 hour value on a glucose tolerance test (GTT) greater than 200. Both tests require patients to fast for a minimum of eight hours prior to being tested. The GTT is a 2 hour series of glucose levels following the administration of a large amount of glucose.

The AACE Guidelines for the Management of Diabetes (link) use A1c of 6.5 or less as a goal for patients once they have been diagnosed with type 2 diabetes.

AACE is a professional medical organization with more than 6,000 members in the United States and 91 other countries. AACE members are physicians who specialize in endocrinology, diabetes, and metabolism.