Just like our weight doesn’t indicate how worthy we are of love, belonging, or joy, neither does our A1c. So then… what is A1c and what does it tell us? I’m Erin, a Registered Dietitian, nutrition therapist, and diabetes specialist based in Seattle, Washington. I am fiercely fat-positive and provide care from a Health At Every Size® approach. This post dives into the A1c- what it measures, how it can be helpful, what its limitations are and what to do when yours changes.
What is the A1c?
A1c is a blood test marker. It gives us the average blood glucose (sugar) levels over the past 2-3 months. For an in-depth explanation of how A1c is measured, check out my interview on the podcast “Can I Have Another Snack?” with Laura Thomas, PhD. (Fast forward to about 26:30 to get straight to the A1c bit. I recommend listening to the whole interview, though -I’ve been told it's really helpful!)
Why is it used in blood work- both routine and in diabetes management?
An elevated A1c means that over the last three months, your body has not been removing glucose from the blood at the usual rate, so the amount in your bloodstream is higher more of the time.
There are innumerable reasons your A1c can change. Aging, changes in life circumstances, stress, illness, other medical conditions, medications, an injury and more can all cause changes in glucose levels or insulin resistance.
Measuring your A1c every so often helps you and your healthcare provider take a peek at what’s going on inside your body. It allows you to make informed decisions about managing your health. Yay! That’s a good thing. Not something you need to be scared of.
Does a certain A1c mean a diabetes or prediabetes diagnosis?
Medical experts have established cut-offs and ranges for A1c that indicate prediabetes and diabetes.
The A1c can give us helpful insight into our body’s functioning. By itself, it does not give us a perfect, infallible, black-and-white picture of what is going on in your body. But it is used in healthcare as evidence for prediabetes (An A1c of 5.7%-6.4% in the United States; 6.0-6.4% in other countries) and diabetes (A1c of 6.5% and higher) diagnoses. Check out this post for more information about prediabetes.
How can the A1c be useful?
The A1c could actually provide some practical and helpful information! Maybe it tells us your body could be really well supported by another medication. Or, perhaps you need to trial a different medication because you don’t like the one you’re on so you take it a little less often than prescribed. Or it could mean it’s time to evaluate your self-care.
Some examples of self-care include: good sleep hygiene (going to bed on time, no doom scrolling in the middle of the night), taking time to grocery shop on Sunday (ugh, my least favorite chore) and getting up to stretch or take a stroll once an hour during your day. Self-care could also mean setting strong boundaries with people in your life. See? Not all lifestyle tweaks are diets. There are so so soooo many factors that can impact your blood glucose levels.
I hope this helps you see that the A1c can be a piece of valuable info. A compassionate, ethical health care provider will help you explore what it could be telling you without making you feel shame or guilt as if your A1c level is “bad” or your fault.
Expected timeline to see a change in A1c
If you and your healthcare provider decide to try a medication to help manage insulin resistance or you discuss some new habits you plan to implement to see what happens with your blood glucose levels, over what kind of timeline should you expect to see changes?
By nature of the type of blood test that A1c is, you will likely do a repeat test in about 3 months. Remember, A1c is measuring your average blood glucose level over the last three months. So to get an assessment of how your average blood glucose levels have changed that is as accurate as possible, wait the full three months to test A1c again.
But remember- most any type of intervention that you try (habits, medications, etc.) is having more immediate impacts on your blood glucose levels. Certain medications will take effect anywhere from hours to days after starting them.
Lifestyle changes can start having pretty immediate changes on your day to day blood glucose levels as well. For example, exercise increases glucose uptake while the muscles are contracting and increases insulin sensitivity for 16 or more hours after the exercise is completed. (Borghouts, 2000)
It is these daily changes in blood glucose levels that will result in a change in the A1c (a measure of the average blood glucose level over the last three months).
Limitations of A1c
Remember how I’ve been repeating that A1c is not perfect or all-encompassing? Here are a few limitations of this test and things to keep in mind when you’re looking at test results.
It’s normal for it to vary between what's done in the clinic (called POC or point of care testing), what's done in the lab, and what is calculated from a continuous glucose monitor. A variation of <10% is considered acceptable (Little, et al., 2011). To put this in perspective, a variation of 9% would be the difference between an A1c of 6.3 (prediabetes range) and 6.87 (diabetes range).
It only tells us an average. It doesn't tell us how high or how low glucose levels are. I compare it to reading a synopsis plus a review of a movie vs. actually watching the movie. It is helpful to get an overall idea of what's going on, but doesn't tell the whole story and may exclude important details.
Certain medical conditions like anemia and hemoglobin variants can result in falsely high A1c levels (Wright & Hirsch, 2017)
There is some controversy about how A1c levels may vary with race/ethnicity independent of what is actually going on with blood sugar levels. It was previously thought that race played a part in this, but researchers are now saying "it is important that we do not use race or ancestry as proxies for poorly understood genetic differences." This is a step in the right direction in the medical field, which I attribute to the incredible activism by our BIPOC colleagues and allies who have helped us understand that differences in health outcomes cannot be attributed to race, just like we cannot use phrenology as credible scientific evidence. What this means to me is that we need to do a better job of looking at A1c as one piece of the puzzle, and utilizing other technology like continuous glucose monitors to make treatment decisions for diabetes (ADA, 2024). (Note: I don’t recommend continuous glucose monitors for people without diabetes, but that is a whole other blog post!)
The takeaway here is: Remember that the A1c always needs to be used in collaboration with other metrics to make a diagnosis.
Important reminders no matter your A1c
Try not to freak out. Stress can impact blood glucose levels! Regular stress management practices are encouraged.
Your body still needs nourishment. You do not need to immediately start a new diet plan. Your body NEEDS food to fuel it. If you get A1c test results back and it scares you into thinking that you immediately need to cut down on carbohydrates or start eating less calories, stop! Take a deep breath and employ self compassion. Repeat the mantra, “My body deserves to be nourished.”
Remember that you are deserving of good things, you are worthy of love and you can work towards accepting your body exactly as it is. A1c is just a number.
Just. A. Number.
Borghouts LB, Keizer HA. Exercise and insulin sensitivity: a review. Int J Sports Med. 2000 Jan;21(1):1-12. doi: 10.1055/s-2000-8847. PMID: 10683091.
Little, Randie R., Curt L. Rohlfing, and David B. Sacks. "Status of hemoglobin A1c measurement and goals for improvement: from chaos to order for improving diabetes care." Clinical chemistry 57.2 (2011): 205-214
Wright, Lorena Alarcon-Casas, and Irl B. Hirsch. "Metrics beyond hemoglobin A1c in diabetes management: time in range, hypoglycemia, and other parameters." Diabetes technology & therapeutics 19.S2 (2017): S-16.
American Diabetes Association Professional Practice Committee; 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2024. Diabetes Care 1 January 2024; 47 (Supplement_1): S20–S42. https://doi.org/10.2337/dc24-S002