Posted by Eva M. Vivian, PharmD, BCPS, CDE, BC-ADM - July 13, 2009 - 2:05 p.m. ET
Last month at the American Diabetes Association's (ADA) Scientific Sessions, an expert committee recommended the use of the hemoglobin A1C assay for the diagnosis of diabetes.

Hemoglobin A1C is a more stable chemical moiety than glucose. Measuring A1C is convenient and easy for patients because fasting is not required. In addition, there is a strong correlation between A1C and the risk of developing retinopathy.

However, this recommendation continues to be controversial and will no doubt be the subject of many conversations to come. It is important to note that previous methods of diagnosis are still acceptable—especially in settings where A1C testing is unavailable or inaccurate.

ADA encourages use of eAG

The recommendation to use A1C as a diagnostic tool is also related to another topic that diabetes care providers have been discussing: the ADA's call to use an eAG to report and discuss glucose control with patients.

A1C is traditionally reported as a percentage, but the recent ADAG (A1C-Derived Average Glucose) study developed a formula that makes it possible to report the A1C in mg/dl or mmol/l units, which are the units that patients are used to seeing when testing their blood glucose at home.

The reporting of eAG can help pharmacists educate consumers about their control by using measurements /units that are most familiar to them. It may help bridge the gap between the patient's understanding of laboratory tests and the numbers from their blood glucose meter.

Two changes would be required before laboratories could implement this formula: 1) A1C would have to be reported as a percentage, in IFCC units (mmol/mol), and as an eAG.2) Health care professionals would have to adopt the new term to use with patients when discussing diabetes management and glucose control.

The ADAG formula that is used to calculate the eAG from A1C result is: 28.7 xA1C – 46.7 = eAG. For example, an individual with an A1C of 7% would have an eAG of 154.2 mg/dl (28.7x7-46.7=154.2 mg/dl).
A1C eAG
% mg/dl mmol/l
6 126 7.0
6.5 140 7.8
7 154 8.6
7.5 169 9.4
8 183 10.1
8.5 197 10.9
9 212 11.8
9.5 226 12.6
10 240 13.4