A1C is a blood test performed by a healthcare professional to measure an average of blood sugar levels over the past 2-3 months. If you have been diagnosed with prediabetes or diabetes, you have probably had your A1C tested. This is a helpful tool for understanding your overall blood sugar control, allowing you and your healthcare provider to see if there are trends between each visit and evaluate how your current diabetes treatment plan is working.
Since A1C is measured as a percentage, this value can be harder to interpret as compared to a blood sugar value, like the one you’re used to seeing on a blood glucose meter. You can use an A1C calculator to give you a sense of how an A1C percentage correlates to an average blood sugar value and vice versa. Before you use the calculator, it may be helpful to understand what A1C tells you and what affects it.
- A1C calculator
- What does A1C measure?
- Frequency for A1C testing
- A1C ranges and goals
- Glucose averages and A1C
- What can improve A1C levels?
A1C calculator
Note: This calculator is not a replacement for an A1C lab test and should not be used to make treatment changes. Discuss this information and any questions with your healthcare provider, regarding your unique diabetes self-management plan.The correlation between A1C and average glucose has been studied by Nathan, et al,2008, 1473-1478.*
What does A1C measure?
You may be wondering what makes this test different, especially if you already check your blood sugar multiple times a day. The A1C test goes by a few names, including glycosylated hemoglobin, glycated hemoglobin, or hemoglobin A1C (HbA1c). All of these names hint at what is being measured — the amount of sugar (glucose) attached to hemoglobin.
Hemoglobin is a protein found inside red blood cells, and its job is to carry oxygen to the lungs and all of the cells in your body. Glucose enters your blood stream and sticks, or “glycates,” with the hemoglobin. The higher your blood glucose, the more sugar-coated or “glycated” the hemoglobin becomes.
Since the lifecycle of a red blood cell is about four months, the A1C percentage reflects average blood sugar levels detected on hemoglobin cells of varying ages — days, weeks, or months old. If your blood glucose control has generally been steady, your hemoglobin cells will not be highly sugar-coated, or “glycated,” leading to a lower A1C value.
How often should you have an A1C lab test?
Your healthcare provider may order an A1C test every three months to monitor diabetes treatment changes, such as adjustments to medications, insulin pump settings, or other areas of diabetes self-management. If your blood glucose is within range and stable, your healthcare provider may only order the test every six months.
If you have not been diagnosed with diabetes, sometimes A1C is used along with other measures to help diagnose diabetes. It may also be used as a baseline measurement for people with a strong family history of diabetes or other risk factors to see if levels are increasing over time.
What are A1C ranges and goals?
The lower the A1C value, the less glucose there is coating the hemoglobin. The higher the A1C value, the more glucose there is on the hemoglobin. So higher A1C levels typically correlate with higher circulating blood glucose levels.
A1C ranges
According to the CDC, a normal A1C level is below 5.7%. This is what would typically be expected for someone who does not have diabetes. If your body becomes less efficient at moving glucose into your cells to be used for energy, or insulin resistant, then levels may increase from 5.7% to 6.4%, which is considered prediabetes. Those with levels from 6.5% and above are considered to have diabetes.
If you’ve been diagnosed with diabetes and an A1C test is used to help monitor your diabetes management, not everyone agrees on the ideal number to aim for:
- The American Association of Clinical Endocrinologists recommends an A1C of less than 6.5%.
- The American Diabetes Association recommends an A1C of less than 7%.
- The American Academy of Family Physicians recommends that people with type 2 diabetes aim for an A1C less than 7-8%.
A1C goals
Your healthcare provider can advise you on an individualized A1C goal that takes into consideration factors such as:
- Your age
- Risk of hypoglycemia
- Willingness to spend time working on diabetes self-management
- Financial access to tools such as test strips, medications, insulin, insulin pumps, and CGMs
- Any other current health issues as well as your personal goals
There are some conditions that can affect A1C levels, which your healthcare professional will be aware of, including anemia and sickle cell disease.
A1C results are not good or bad, they are information. Living with diabetes brings many challenges, and some aspects of controlling blood glucose can be out of your control, such as pain from an injury, stress, not being able to eat on time, and more. Don’t be afraid to look at your A1C number — in fact, you should ask about your lab result at each office visit. When it comes to diabetes self-management, the more information you have, the better.
How does A1C relate to glucose averages?
Average from a glucose meter
Although an A1C level gives you a sense of average glucose levels over the past few months, a person with type 1 or type 2 diabetes needs a blood glucose meter to check blood sugar and make treatment decisions on a day-to-day basis.
If you test often during the day — like before and after meals and other times that your blood sugar can vary — and use an accurate glucose meter, this can give you valuable information on daily variations in blood sugar levels. Many blood glucose meters are also equipped to provide 7, 14, 30, or 90-day averages. A 90-day average on your meter can be used in the calculator above to estimate how it may correlate to an A1C.
Glucose meter averages are based on the frequency that you have tested per day, so if you do not have many data points (i.e. testing infrequently or not during high or low blood sugar swings) or are unable to test at certain times (i.e. like while you’re sleeping), it probably won’t give you a full picture of your blood sugar levels and may skew lower than an A1C test result.
Estimated average glucose (EAG)
The American Diabetes Association (ADA) recommends using an estimated average glucose (EAG) for correlating your A1C percentage into an average that’s a more familiar unit of measure. The ADA has studied how A1C and EAG are related, which is the basis for the A1C to EAG calculator above. The EAG value from the A1C calculator tells you how your blood glucose numbers are averaging in a unit of measure that is familiar, like on a blood glucose meter.
This value should not be used for treatment decisions, but rather for helping you correlate A1C to an estimated average glucose to give you a better idea of how close you are to your target ranges. If your A1C is higher, your EAG is also going to be higher. Or if your A1C is lower, your EAG is going to be lower, so these two numbers will track similarly.
What can you do to improve your A1C levels?
- Partner with your healthcare provider. Ask if you need changes to your medication, insulin or insulin pump settings. If you haven’t had a recent visit with a Certified Diabetes Educator, ask for a referral so that he/she can recommend small changes that can make a big difference.
- Create routines. Try to test with a blood glucose meter, take medications or insulin, and exercise at about the same time each day. This helps create habits so that you don’t forget your self-care activities and helps your healthcare provider identify patterns in your blood sugars.
- Get more data. Test blood glucose more frequently and make sure to check two hours after the start of a meal as often as possible, not just before meals. These after-meal readings are most closely linked with your A1C number and tell how well your body handled the meal.
- Make course corrections quickly. If you find that you are always having a low blood sugar before dinner, add an afternoon snack. If your blood sugar is high, drink lots of water and take a walk (as long as your number is below 250mg/dL, if higher, do not exercise). If you have two readings over 250mg/dL in a row, notify your healthcare provider. Taking action while you are out of range can help you find your way back in target faster.
- Tighten up your carbohydrate counting. Use a kitchen scale to help measure accurate portions of carbohydrate foods. Read labels and use tools that help you carb count, not carb guess. Using an app like Calorie King to look up the exact carb content of foods, and visiting a Registered Dietitian Nutritionist for an individualized meal plan and carb counting review can be great steps to help you get on track.
- Reduce stress. Stress can raise blood sugar, so find ways to relax. Take a walk, read a book, laugh with a friend, find a yoga and/or mindfulness class, or visit a therapist for support. This is all part of self-care, especially when you are living with diabetes.
- Increase activity, even in small amounts. Walking for ten minutes after each meal has been shown to improve blood glucose. Be active and keep moving even by walking the dog or cleaning the house.
People often wonder how long it will take to improve their A1C number. By following your diabetes self-care plan, you can improve your A1C by your next three-month check. Your A1C may continue to go down at each visit if you continue to partner with your healthcare provider and follow the tips above.
It’s not helpful to test your A1C more frequently than every three months, and more frequent testing is not always covered by insurance. If you feel like you have followed your healthcare provider’s recommendations but your A1C level is high, don’t take it personally. Again, there are many factors that make diabetes management difficult, and if you continue to work on it, your number will come down.
In summary, the A1C test gives you a picture of your overall glucose levels. There is no bad or good number, just information that helps you and your healthcare provider understand how well your diabetes management plan is working.
Using an A1C calculator can give you an idea of how your A1C translates into an EAG number that you can recognize, using the same unit of measurement as shown on a blood glucose meter. However, remember that A1C goals can be different for each person based on age, treatment goals, access to diabetes supplies, and other health issues present, so don’t be afraid to talk with your healthcare professional about setting your unique goals to lead to better diabetes management.
*Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ. “Translating the A1C assay into estimated average glucose values.”Diabetes Care.2008;31(8): 1473-1478.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2742903/
