By Bruce Sylvester
NEW ORLEANS -- June 6, 2009 -- A patient who reaches a glycosylated hemoglobin (Hb A1C) level of 6.5% should be diagnosed as a diabetic, according to a committee of experts from around the world meeting at the American Diabetes Association (ADA) 69th Scientific Sessions. This measurement, they added, should become a new international standard for the diagnosis of diabetes.
"A1C is a better measurement, technically, and in terms of convenience when compared to current glucose measurements -- and A1C correlates closely with the risk of diabetic retinopathy," said David M. Nathan, MD, Diabetes Center, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts. Dr. Nathan chaired the expert committee presentation here on June 5.
There are presently 2 standard tests used to diagnose diabetes: the fasting plasma glucose test or the oral glucose tolerance test. The committee examined the correlation between long-term glycaemic elevations and neuropathic complications like retinopathy, and found that Hb A1C, measuring average blood-glucose control over the past 2 to 3 months, would be a better diagnostic tool.
"We wanted a measure that would indicate where clinical complications could ensue, and elevation above Hb A1C 6.5% is where the danger of diabetic retinopathy actually begins," Dr. Nathan noted.
For individuals with an elevated risk of developing diabetes (genetically or due to obesity), the committee noted that an Hb A1C of 6% but less than 6.5% is likely to put these individuals at highest risk.
Paul Robertson, MD, president for medicine and science of the ADA, added comments at a press briefing after the guidelines were presented. He said that his organisation will develop a task force to study the report and to assess the new recommendation. The ADA did release an announcement on June 5, officially acknowledging the potential significance of Hb A1C as a potential diagnostic tool without officially endorsing the recommendations of the committee yet.
The report of the international expert committee was published online ahead of print on June 5 at http://care.diabetesjournals.org; it will appear in the July issue of Diabetes Care.
Diabetes experts on the committee represented the ADA, the International Diabetes Federation, and the European Association for the Study of Diabetes.