The Ultimate Guide to A1C

A1C blood test being held by latex gloved hand | A1C charts | A1C chart | A1C range prediabetes

Updated 9/9/22

Read time: 6 minutes

  • The A1C test is a blood test used to diagnose diabetes and assess how well someone is managing their diabetes. 
  • A healthy A1C for most people with diabetes is less than is 7.0%.
  • Check out our A1C chart below for a breakdown of what A1C is and A1C to average blood glucose conversions.

What is an A1C test? 

The A1C test is a blood test used to diagnose diabetes and assess how well someone is managing their diabetes. Your A1C value is a number that reflects your average blood glucose (BG) over the past two to three months. Red blood cells live two to three months, and A1C reflects the hemoglobin's exposure to glucose over that time.  

To help better understand all those numbers, we've come up with this guide.  Remember that your A1C and average blood glucose don't exactly match. For extra help understanding what these numbers mean, you can also track and get help from your clinical health coach in the One Drop app. All One Drop coaches are certified diabetes care and education specialists (CDCES) with expertise in helping people understand and improve their A1C.

See the detailed A1C chart below to set goals for future A1C test results and learn more about about A1C. 

Why Your Average Blood Sugar Might Not Match Your A1C

What is an Ideal A1C?

An ideal A1C for most people with diabetes is less than 7.0%. Speak with your doctor to learn what a healthy A1C is for you.

Think of A1C like a compass. Not only can it identify prediabetes and diagnose diabetes, but it can assess how well your treatment is working over time.

Living with diabetes means living with numbers. Lots of numbers. 

Take A1C, for example. What is A1C? The hemoglobin A1C (“HbA1C” or "A1C") blood test is used to diagnose diabetes and assess how well someone is managing their diet, food, activity, and blood glucose levels.

  • But what is A1C?
  • What are the A1C ranges that define prediabetes and diabetes?
  • What causes your A1C numbers to rise?
  • How do you convert A1C to average blood glucose?

A1C Chart and Guide

A1C measures the total amount of glucose that has attached to your hemoglobin over time. 

This amount is reflected as a percentage (e.g. 70%) or as a ratio (e.g., 53 mmol/mol).

See the A1C chart below for A1C to average blood sugar conversions in an easy reference table. The sections are for A1C numbers in the non-diabetic range, the prediabetes range, and the diabetes A1C range.


Infographic all about A1C | A1C charts | A1C chart | A1C range prediabetes


What Does Estimated A1C Mean and How Is It Different From an A1C in a Lab? 

Estimated A1C (eA1C) is an estimate of your current A1C level. It is calculated using your last 30 days of logged glucose values (from a glucose meter or CGM) and provides an A1C estimate. The more glucose values you provide, the more accurate your eA1C will be.

An A1C done in a lab is the most accurate and provides your average blood sugar level over the last two to three months. 

The table below converts the average of self-monitored blood sugar readings (or readings from a CGM) to eA1C values. This can be helpful in providing a glimpse into what your A1C might be. Knowing your eA1C provides general information about how well you're managing your health.

How to Lower A1C Without Medication

What Are the Pros and Cons of Estimated A1C Versus My A1C at the Doctor's Office? 

A lab A1C is more accurate than an eA1C, but an A1C level in a lab or at your doctor’s office can only be checked every few months. An eA1C in our app can be viewed daily.

No matter what your eA1C is, you’re in the right place for support. We’re here to help you meet and maintain your health goals.

How Does One Drop Set My Initial Estimated A1C Goal? 

If you have identified that you have diabetes, we set your initial estimated A1C goal at less than 7% (53 mmol/mol) based on guidelines from the American Diabetes Association for people with diabetes who are not pregnant.

If you have identified that you have prediabetes, or are at risk for diabetes, we set your initial estimated A1C goal at less than 6.4% (46 mmol/mol). An A1C of 6.5% (48 mmol/mol) or above is in the diabetic range. You are welcome to adjust your A1C goal.

We recommend that you talk with your doctor to identify what A1C target is appropriate and safe for you based on your medical history.

How Does One Drop Calculate My Progress? 

We calculate your estimated A1C using an average of the glucose measurements you’ve entered in the app over the last 30 days. The more glucose values you provide, the more accurate your estimated A1C will be.

We calculate change in your estimated A1C by comparing your most recent seven days of blood sugar readings with your first several readings. Because of this, it can take eight days to start seeing progress on your A1C goal screen.

How Do I Know If I Should Adjust My Goal? 

Speak with your doctor to help identify a goal that’s safe for you. If you have a question about whether you should adjust your estimated A1C goal, start a chat with your One Drop CDCES.

What Should I Consider When Setting A Goal? 

Think about what is safe and realistic for you. Then, choose a small manageable target based on how it could fit into your lifestyle.

If you’d like additional support in setting a goal, reach out to your coach.

What Are Some Strategies to Achieve My A1C Goal? 

You might find that reaching your A1C goal means paying attention to the following:

Note how these areas affect your A1C and make adjustments as needed.

What Do I Do When I Achieve My Goal? 

If you’ve achieved your goal, consider reflecting on the following:

  • What changes have I made to get here?
  • What changes were easy? Which were challenging?
  • Do I feel like they were the best changes for me?
  • What differences do I notice about my body and my mind? 
  • How can I maintain the changes I’ve made?
  • What other strategies do I want to try on my journey toward better health?

Note: With your healthcare provider, determine what targets are best for you based on your lifestyle and needs. If you’re not sure what your targets should be, ask your provider at your next visit.

This article has been clinically reviewed by Lisa Graham, RN, CDCES, clinical health coach and director of clinical operations at One Drop.

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One Drop Team
Apr 24, 2019

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