The A1c test (also called the HbA1c test), which establishes average blood sugar levels over a three-month period, should replace fasting plasma glucose and oral glucose tolerance tests as the standard for diagnosing diabetes.
That’s the recommendation of an internal committee of experts appointed by the American Diabetes Association, the European Association for the Study of Diabetes, and the International Diabetes Federation. The committee, reporting at the 60th Scientific Sessions of the ADA, offered several reasons for its recommendation:
- The A1c test establishes a two- to three-month average that is a more reliable figure than the “snapshot” numbers derived from a fasting plasma glucose or oral glucose tolerance test.
- The test is easier on patients, who do not have to fast or do anything out of the ordinary other than give a blood sample.
- The test is more resistant to loss of useful information than either of the glucose tests. For example, if blood samples from the fasting or tolerance tests take too long to reach a laboratory, they lose any measurable glucose. A1c samples, in contrast, retain their measurable constituents.
The committee reported that it has set an A1c of 6.5% as the “cut point” for diagnosing diabetes. In other words, individuals with A1c levels of 6.5% and above are considered to have the disease. Individuals with A1c levels running more than 6%, but not quite as high as 6.5%, are considered at high risk of developing type 2.
The committee also said that many doctors already independently undertake A1c testing on their patients because of its reliability and depth of data. Although making the A1c the new standard assay for diabetes would be a major departure, many members of the medical community would apparently have no problems making the transition to it.