Blood Glucose

A1c vs Estimated Average Glucose (eAG)

January 11, 2017   /

A1c vs Estimated Average Glucose (eAG)

What is A1c?
A1c also is known as glycated hemoglobin or HbA1c. It measures your average blood glucose for the past 3 months. People with diabetes should have their A1c level checked every 6 months. The A1c goal is less than 7%.

Why do I need an A1c test if I check my blood glucose at home?
Think of the blood glucose number that you get at home as a photo—it is what your blood glucose was at that single moment. Think of A1c as a video camera that runs continuously—it tells you what your average blood glucose was over the past several months. However, you still need to check your levels at home, because you cannot adjust your insulin, diet, exercise program, etc, based on A1c levels.

Why not just use the A1c level?
In one study, 66% of people with diabetes did not know their A1c result and only 25% accurately recalled what their A1c level was within 1% of the real result. A1c is useful to medical professionals, but it basically does not mean much to the average person.

What is estimated average glucose (eAG)?
The eAG is a way of reporting A1c results to patients in the same units that are used for checking blood glucose levels at home, in milligrams (mg)/deciliter (dL).

Comparison of A1c and eAG Levels

A1c %

eAG (mg/dL)

eAG (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

*millimoles/liter

Why is this chart different from other charts that I have seen?
The American Diabetes Association® Standards of Care chart showing the correlation between A1c and mean glucose levels was based on a study, the Diabetes Control and Complications Trial (DCCT), which looked at quarterly A1c tests and 7-point glucose measurement in 1400 patients with type 1 diabetes only. This chart resulted from the International A1c-Derived Average Glucose Study (ADAG). This study involved people with type 1 diabetes, type 2 diabetes, and people who were not diagnosed with diabetes. It also looked at people from various ethnic and racial groups. Continuous glucose monitors were allowed during the ADAG Study, while they were not available at the time that the DCCT Study was completed.

What is the formula for turning A1c into eAG?
A1c×28.7–46.7=eAG

 

References and recommended readings
American Diabetes Association. Estimated average glucose: an alternative to A1C. Available at: http://professional.diabetes.org/Content/Average_Glucose_Q_A%20final.doc. Accessed June 22, 2012.

Nathan D, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ. Translating the A1C assay into estimated average glucose values. Diabetes Care [serial online]. 2008;31:1473-1478. Available at: http://care.diabetesjournals.org/content/31/8/1473. Accessed June 22, 2012.

Review Date 6/12
D-0583

 

D_0583_A1c_vs_Estimated_Average_Glucose_eAG.doc