Estimated Average Glucose vs. A1C – How Do They Compare?

If you have diabetes, you know it's important to track your blood sugar or blood glucose levels to help manage your disease.  Now, doctors have a new way compare your daily glucose readings with your long-term average readings from an A1C test.  The new method is known as your Estimated Average Glucose or eAG.

When you have blood drawn or prick your finger to check your blood sugar, the meter reports how many milligrams of sugar are found in each deciliter of blood (mg/dl).  This test tells you how much sugar is in your blood at that precise moment, which can help determine what you should eat or how much insulin you need to take.

The A1C test is a blood test used by doctors to determine your average blood sugar level over the last two to three months. A1C results are reported as the percentage of hemoglobin in the blood that has sugar attached to it. This value is important because it provides a better picture of your overall sugar control.  If your A1C percentage is high, your sugar was not well controlled over the past 2 to 3 months.

The confusion with these two tests lies in the fact that they don’t report their results using the same scale.  That means the numbers don’t directly relate to each other, which is why the American Diabetes Association (ADA) has introduced the new term eAG.  The eAG score is another way to talk about your long-term blood sugar level using the same number system that you see on your daily glucose meter readings – mg/dl.

The American Diabetes Association provides a quick reference eAG chart that will let you translate your A1C percentage rounded to the nearest half-percent into the eAG score.  The page also includes a calculator where you can enter your exact A1C for a more precise reading on your eAG.

Many glucose meters can provide an average of your readings for the last several weeks or months. It’s important to understand that this average is not the same as your eAG.  Although you may feel like you are constantly testing your blood, in actuality, your glucose meter cannot provide an average of what your glucose level was between all those tests.  You could have had a very high sugar level, taken insulin, and had your sugar drop very low between meter readings.  But the meter will only read your sugar at the moment you sample your blood.

It’s also important to remember that your A1C percentage or eAG score is the average of your glucose levels.  These numbers cannot help you decide what to eat or how much insulin to take at a particular moment.  But combined with your daily meter readings, they can help you and your doctor decide on your overall sugar control plan to get the best control of your disease.

Denise DeWitt is a freelance writer for


American Diabetes Association. Estimated Average Glucose (eAG). Web. August 6, 2012. Type 1 Diabetes. Estimated Average Glucose (eAG). Gary Gilles. Web. August 6, 2012.


Care Diabetes Journal. Translating the A1C Assay Into Estimated Average Glucose Values. David M. Nathan, MD et al. Web. August 6, 2012.



Related Links:


Diabetes and the A1C Test


Diabetes: Using A Blood Glucose Meter


Type 1 Diabtes

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