From HbA1c to estimated average glucose: making life easier for patients, physicians

American Diabetes Association 68th Scientific Sessions

There is now a new term to express HbA1c levels. Data released on Saturday indicate that "estimated average glucose" is a reliable mathematical translation of HbA1c levels.

The International A1C-Derived Average Glucose study, or ADAG, was an international multicenter trial that analyzed the relationship between average glucose level and HbA1c level over the preceding three months to determine whether HbA1c could be reliably reported as average glucose, in the same units used for self-monitoring.

"The whole idea behind it is to simplify education in clinical practice," Robert J. Heine, MD, PhD, professor of Diabetology, VU University Medical Center, Amsterdam, said during a press conference.

ADAG analyzed 507 patients from 10 international centers around the world (268 with type 1 diabetes, 159 with type 2 diabetes and 80 with no diabetes). Average glucose was calculated by combining weighted results from at least two days of continuous glucose monitoring performed at least four times and seven-point daily self-monitoring of capillary glucose performed at least three days per week. In all, 2,700 values were obtained from each individual.

"Eestimated average glucose will not replace HbA1c," said David M. Nathan, MD, professor of medicine, Harvard Medical School,.

Estimated average glucose will be reported in the same units as self-monitoring. Now, physicians will be able to obtain reports both in HbA1c units and estimated average glucose units (mg/dL or mmol/L), according to Nathan.

For example, target HbA1c of 7% will be expressed as 154 mg/dL using the new estimated average glucose, in contrast with 170 mg/dL based on old ADA estimated average glucose.

“At the end of the day, just one number will be applied in clinical practice – the estimated average glucose. This will make life much easier for the patient,” Heine said.

The ADAG Study Group conducted this analysis because the International Federation of Clinical Chemists came up with a new way to standardize the HbA1c assay and “was going to be yet another set of units which we thought would be incredibly confusing for patients and providers,” Nathan said.

The ADAG findings will be printed in the August issue of Diabetes Care. – by Katie Kalvaitis

As a certified diabetes educator, I know firsthand of how much time it takes for people with diabetes to manage it. Blood glucose monitoring is the key that helps people to find out ‘What target do I need to meet to keep me healthy over the long-term?’ We now have this user-friendly term – estimated average glucose – where we can be making things a little more user-friendly and day-to-day… it really does tell them what their long-term control is. Anything we can do in that way to help the 21 million people we know to have diabetes is very positive.

– Susan McLaughlin, RS, RD, CDE, CPT

President-Elect, Health Care & Education, American Diabetes Association

For more information:

Horton ES. Estimated average glucose.

Nathan DM, Kuenen J, Borg R, et al. Translating the A1C assay into estimated average glucose values. Diabetes Care. 2008:31:1-6.

Both presented at: American Diabetes Association 68th Scientific Sessions; June 6-10; San Francisco.