What is the A1C test?
A1C is a blood test that tells you what your average blood sugar (blood glucose) levels have been for the past 2–3 months. It measures how much sugar is attached to your red blood cells. If your blood sugar is frequently high, more will be attached to your blood cells. Because you are always making new red blood cells to replace old ones, your A1C changes over time as your blood sugar levels change.
What is eAG?
eAG stands for estimated average glucose and is your estimated average blood sugar. This number translates an A1C test result into a number like the one you see when you test your blood sugar at home. For example, an A1C of 7% means that your average blood sugar for the last two to three months was about 154 mg/dL.
What does an A1C/eAG result mean?
Usually, your A1C gives you a general trend in your blood sugar that matches what you see with your day-to-day blood sugar checks. Sometimes, however, your A1C result may seem higher or lower than you expected. That may be because you aren’t checking your blood sugar at times when it’s very high or very low.
Use this chart to understand how your A1C result translates to eAG. First, find your A1C number on the left. Then read across to learn your average blood sugar for the past 2–3 months.
| A1C | AVERAGE BLOOD GLUCOSE (eAG) |
|---|---|
| 6% | 126 mg/dL |
| 6.5% | 140 mg/dL |
| 7% | 154 mg/dL |
| 7.5% | 169 mg/dL |
| 8% | 183 mg/dL |
| 8.5% | 197 mg/dL |
| 9% | 212 mg/dL |
| 9.5% | 226 mg/dL |
| 10% | 240 mg/dL |
| 10.5% | 255 mg/dL |
| A1C | AVERAGE BLOOD GLUCOSE (eAG) |
|---|---|
| 6% | 126 mg/dL |
| 6.5% | 140 mg/dL |
| 7% | 154 mg/dL |
| 7.5% | 169 mg/dL |
| 8% | 183 mg/dL |
| 8.5% | 197 mg/dL |
| 9% | 212 mg/dL |
| 9.5% | 226 mg/dL |
| 10% | 240 mg/dL |
| 10.5% | 255 mg/dL |
How often should I have What if my A1C is different an A1C test? from what I expected?
Usually your doctor will measure your A1C at least twice a year. If your medication is changing, if you are making other changes in how you take care of yourself, or if other things might be affecting your blood sugar, you may have it checked more often.
What is a good target for A1C?
The American Diabetes Association recommends a target A1C of less than 7% for most adults. You and your doctor may decide on a higher or lower target depending on your treatment goals and other factors. The closer you get to your target, the better your chances of preventing or delaying problems from diabetes that can develop over time. Studies have shown that, for every 1-point decrease in A1C levels, you reduce your risk of long-term diabetes complications by up to 40%.
DO I STILL NEED TO CHECK MY BLOOD SUGAR WITH A METER IF I GET THE A1C TEST REGULARLY?
Yes. Both kinds of checking are important. You’ll use your meter results to make day-to-day decisions. The A1C gives you an overall idea of what’s going on and how your treatment plan is working at the times you aren’t checking your blood sugar.
What if my A1C is different from what I expected?
If your A1C is different from what you expect, talk to your doctor. You may need to check your blood sugar more often or use a continuous glucose monitor (CGM) to get a better idea of how your blood sugar is changing throughout the day.
This handout was published in Clinical Diabetes, Vol. 41, issue 1, 2023, and was adapted from the American Diabetes Association’s Diabetes Advisor handout “Understanding Your A1C Test.” Visit the Association’s Patient Education Library at professional.diabetes.org/PatientEd for hundreds of free, downloadable handouts in English and Spanish. Distribute these to your patients and share them with others on your health care team. Copyright American Diabetes Association, Inc., 2023.
