http://hemoglobin-research.blogspot.com/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.