What is HbA1c?
Medically reviewed by Neka Miller, PhD on March 25, 2021. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
If you have a diagnosis of prediabetes or diabetes, you may have heard your healthcare provider mention “A1c” or “HbA1c.” However, you might not know exactly what it is, so here we’re answering the question, “What is HbA1c?”
Read on to learn more about HbA1c, what it indicates, and what can contribute to a high HbA1c number. You’ll also learn how HbA1c is used to test for prediabetes and diabetes and what you can expect when you undergo this type of testing. (Note that you can check your HbA1c levels from the convenience of home with the Everlywell at-home HbA1c Test.)
What does HbA1c mean?
Your HbA1c number is an indicator of the average sugar level in your blood over the past 3 months. HbA1c is also known as A1c or glycated hemoglobin.
Hemoglobin is the part of a red blood cell that carries oxygen from the lungs to other parts of the body. HbA1c testing is a way of measuring how much blood sugar, or glucose, is attached to your hemoglobin (expressed as a percentage). Because red blood cells typically only live for around three months, HbA1c results provide information about your average blood sugar level over the last 90 days.
An HbA1c test result is not the same as the glucose result you get from a blood glucometer (or “glucose meter”). A glucometer determines your at-the-moment blood sugar level, which often swings up and down throughout the day as you eat and exercise.
Because an HbA1c test shows your average blood sugar level over the past several months, it’s a reliable and consistent way to monitor long-term changes in blood sugar. It’s also a common test used by healthcare professionals to diagnose diabetes. However, this test is not a replacement for regular blood glucose monitoring in diabetic patients.
Why would I need HbA1c testing?
In certain clinical contexts, the HbA1c test is useful for diagnosing prediabetes or type 1 and type 2 diabetes. Checking your average glucose level from the past 3 months may help a healthcare professional understand if you are diabetic or are at risk of developing diabetes (due to having prediabetes, or a blood sugar level that isn’t quite in the diabetic range but is still significantly higher than normal).
If you’ve already been diagnosed with diabetes or prediabetes, this test may be helpful for monitoring your blood sugar control. Tracking your HbA1c level can help you—and your healthcare provider—assess the effectiveness of your current treatment plan. Monitoring HbA1c levels can also help you see how choices you make—like diet—affect your blood sugar level.
How does the HbA1c test work?
Getting an HbA1c test requires you to provide a blood sample. If you visit your healthcare provider for this test, you’ll have a blood draw or a finger prick to provide a blood sample. Unlike many other blood tests, fasting isn’t necessary for the HbA1c test.
When you receive your A1c level, you’ll notice that it will be reported as a percentage. It’s best to review the test results with your healthcare provider to understand what they mean for you specifically, but the typical HbA1c range is as follows:
- Normal is below 5.7%
- Prediabetes is between 5.7% and 6.4%
- Diabetes is 6.5% or higher
Based on your HbA1c number, your healthcare provider may offer specific recommendations for you based on factors like your age, health, and weight.
What causes a high HbA1c level?
Several different factors can potentially result in a high HbA1c level, and prediabetes and diabetes are among the most common. A high level often indicates diabetes, while a higher-than-average level may predict the risk of developing diabetes in the future.
In addition to diabetes, the following factors may also be associated with an elevated HbA1c level (several of these are also relevant risk factors for diabetes):
- Being overweight or obese
- Smoking
- Alcoholism
- Poor sleep
Testing your HbA1c at home
Knowing your A1c number has never been easier, thanks to at-home HbA1c testing. The Everlywell at-home HbA1c Test only requires a small blood sample from a simple finger prick which you can administer to yourself in the comfort of home.
Just like a test from your healthcare provider, our at-home test allows you to see how well your blood sugar levels have been controlled over the last 90 days. Sharing this information with your healthcare provider can help guide a treatment plan, such as targeted changes to your diet and physical activity levels to improve your blood sugar levels.
References
1. What is diabetes. International Diabetes Federation. URL. Accessed March 25, 2021.
2. Hemoglobin A1C (HbA1c) Test. Medline Plus. URL. Accessed March 25, 2021.
3. Diabetes Mellitus: Management of Microvascular and Macrovascular Complications. Cleveland Clinic. URL. Accessed March 25, 2021.
4. Bae JC, Rhee EJ, Lee WY, et al. Optimal range of HbA1c for the prediction of future diabetes: a 4-year longitudinal study. Diabetes Res Clin Pract. 2011;93(2):255-259.
5. Tsenkova VK, Carr D, Schoeller DA, Ryff CD. Perceived weight discrimination amplifies the link between central adiposity and nondiabetic glycemic control (HbA1c). Ann Behav Med. 2011;41(2):243-251.
6. Soulimane S, Simon D, Herman WH, et al. HbA1c, fasting and 2 h plasma glucose in current, ex- and never-smokers: a meta-analysis. Diabetologia. 2014;57(1):30-39.
7. Lee SWH, Ng KY, Chin WK. The impact of sleep amount and sleep quality on glycemic control in type 2 diabetes: A systematic review and meta-analysis. Sleep Med Rev. 2017;31:91-101.
8. Radin MS. Pitfalls in hemoglobin A1c measurement: when results may be misleading. J Gen Intern Med. 2014;29(2):388-394.
9. Madhu SV, Raj A, Gupta S, Giri S, Rusia U. Effect of iron deficiency anemia and iron supplementation on HbA1c levels - Implications for diagnosis of prediabetes and diabetes mellitus in Asian Indians. Clin Chim Acta. 2017;468:225-229.
10. Radin MS. Pitfalls in hemoglobin A1c measurement: when results may be misleading. J Gen Intern Med. 2014;29(2):388-394.