Understanding A1C

What Is the A1C Test?

The A1C test can be used to diagnose diabetes or help you know how your treatment plan is working by giving you a picture of your average blood glucose (blood sugar) over the past two to three months.

Close-up of person getting blood glucose tested with lancet

How Does the A1C Test Work?

It can identify prediabetes, which raises your risk for diabetes. It can be used to diagnose diabetes. And it's used to monitor how well your diabetes treatment is working over time. It's also a critical step in forming your game plan to manage diabetes with your diabetes care team.

The big picture: monitoring treatment

This relatively simple blood test can tell you a lot. The test results give you a picture of your average blood glucose (blood sugar) level over the past two to three months. The higher the levels, the greater your risk of developing diabetes complications. Your doctor will tell you how often you need the A1C test, but usually you’ll have the test at least twice a year if you’re meeting your treatment goals. If you're not meeting your goals or you change treatments, you may need to get an A1C test more often.

Interpreting Your A1C Results

So, what do the numbers mean?

When it comes to the numbers, there's no one-size-fits-all target. A1C target levels can vary by each person's age and other factors, and your target may be different from someone else's. The goal for most adults with diabetes is an A1C that is less than 7%.

A1C test results are reported as a percentage. The higher the percentage, the higher your blood glucose levels over the past two to three months. The A1C test can also be used for diagnosis, based on the following guidelines:

If your A1C level is between 5.7 and less than 6.5%, your levels have been in the prediabetes range.
If you have an A1C level of 6.5% or higher, your levels were in the diabetes range.

Finally: A1C is also reported as ‘estimated average glucose,’ or eAG

Another term you may come across when finding out your A1C is eAG. Your doctor might report your A1C results as eAG. eAG is similar to what you see when monitoring your blood glucose at home on your meter. However, because you are more likely to check your blood glucose in the morning and before meals, your meter readings will likely be lower than your eAG.