A blood test physicians use regularly to check the average blood sugar levels in people with diabetes is now being recommended as a tool to diagnose the disease. And, the test is much more convenient for patients, as it does not have to be done fasting. Furthermore, I predict that this test will help us doctors identify many of the people with diabetes that don’t know they have it . . . and a whopping 40% of people with diabetes don’t even know they have it! Could you be one of them?
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At the American Diabetes Association’s 69th annual meeting in New Orleans, an international committee of experts announced their consensus that the A1C blood test is an accurate way to diagnose diabetes in adults and children, but not in pregnant women. 
According to these experts, the hemoglobin A1C test should now be the new standard test for diabetes, largely because it is a long-term measurement of chronic blood sugar levels and therefore provides a better diagnosis than current tests. 
The international committee recommended that the A1C assay should be used to diagnose diabetes instead of a fasting plasma glucose or oral glucose tolerance test.
And, the committee recommends patients with an A1C of 6.5% or higher should be diagnosed with the disease, even though the group warned that there is no “absolute dividing line between normal glycemia and diabetes.”
“This is the first major departure from the way we’ve been diagnosing diabetes for more than 30 years,” David M. Nathan, M.D., of Harvard Medical School who chaired the expert committee, told the press at the start of the annual meeting of the American Diabetes Association. 
The A1C assay should now replace the standard fasting plasma glucose test (FPG), as called the fasting blood sugar (FBS), and the less common oral glucose tolerance test (OGTT). 
Unlike the others, the A1C measures average blood glucose over the preceding three months, rather than just at one point in time. 
Proponents say the A1C test gives it two major advantages over the FPG or FBS or OGTT:

• “A1C values vary less than fasting plasma glucose values, and the assay for A1C has technical advantages compared with the glucose assay,” Dr. Nathan said.
• “Also, testing for diabetes using A1C is more convenient and easier for patients, who will no longer be required to perform a fasting or oral glucose tolerance test,” he aid.

The recommendations, made by a convention of the American Diabetes Association, the International Diabetes Federation, and the European Association for the Study of Diabetes, were published online in Diabetes Care and will appear in the July issue.
I, like many primary care doctors, already use A1C screening as a first-line tool for diagnosis. 
“Anecdotally, many physicians are already using it,” added Richard Kahn, Ph.D., chief scientific officer of the American Diabetes Association, who moderated the press conference. “This is not going to come as a surprise to them.” And, it’s no surprise to me. My only surprise is that it’s taken them this long to come out with the recommendation. Dr. Zonszein agreed, saying clinicians have been “waiting years for this to happen,” as many have already been using the A1C test unofficially to diagnose diabetes.
Some practitioners say diabetes specialists have been more likely to stick with the finely-tuned FBG and glucose tolerance measurements, while primary care doctors have been more willing to embrace the A1C. And, that corresponds with what I’ve seen around the country.
With the A1C in place as a standard, the diabetes panel now recommends the test annually for all adult patients who are overweight and have other risk factors, such as family history of diabetes, high blood pressure, or abnormal lipids. 
For people at risk, diabetes screening is recommended every year. Otherwise, diabetes screening is recommended every three years. You can see a nice flow sheet with the old recommendations here. The only change to be made in this chart is to use an A1C test, rather than the FPG, FBS, or OGTT.
To Thomas L. Schwenk, M.D., a professor of family medicine at the University of Michigan, this reflects different approaches to different patient populations. He said the A1C makes more sense in his practice.
“We are dealing with patients with many chronic problems and the obvious need for major lifestyle modifications, as well as managing six to eight medications directed at metabolic syndrome, not making decisions about tweaking insulin dosages by a couple units,” he declared.
From a practical standpoint, Christopher D. Saudek, M.D., a Johns Hopkins endocrinologist, likes the idea that the A1C measures average blood glucose over time, rather than at a particular moment.
He said that makes it “less susceptible to patients ‘tuning up’ before they see a doctor [by] watching their diet for a day or two.”
In the end, he predicted, the A1C test will help “chip away at the 40% of people with diabetes who don’t know it.” And, I agree.
If you have not had diabetes screening, I’d recommend you discuss it with your physician at your next office visit.