What is A1C and why does it matter?

Chances are that if you have ever had bloodwork, you likely have had your HbA1C checked.

If you have, you may or may not have known why, what it is, why it matters to your health and what to do with that information.

So, let’s dive into it a bit!

But first, keep it mind that the information in this post is not meant to diagnose a condition, nor it is meant to be used to guide your individual treatment or management of your health. Speak to your healthcare team for personalized advice.

Glucometer showing a capillary blood sugar reading in US measurements. This tool does not measure A1C.

First, is there a difference between HbA1C, A1C and A1C%?

No, they’re the same thing. All three terms refer to hemoglobin A1C, or glycated hemoglobin, which is a blood test related to blood glucose and often used to diagnose diabetes or track diabetes management. We’ll use the term A1C in this blog post.

What does A1C measure?

At its most simple, A1C measures your average blood sugar over the past 3 months. That being said, there is more to it than just that; the past 30 days prior to the test contribute more significantly, about 50% of the A1C%, which means if you are a creature of habit except during the month of December, an A1C blood test performed in January will be much more heavily influenced by the month of December than an A1C performed in February or March.

Don’t take this as encouragement to delay your testing after holidays or vacations! Just an example of how an A1C may change month to month but not significantly day-to-day.

In more complex terms, A1C essentially measures what percentage of hemoglobin in your blood is covered with sugar. A fabulous description I’ve heard is to think of a glazed donut; a lower A1C within your individual target range is like a donut with a light glaze; whereas a higher A1C is like a donut with a thick sticky frosting. Even though those red blood cells live the same 90 days, more sugar was in the blood and available to build up on that second donut.

How often will my A1C be tested?

This will depend on various factors like your age, family history, risk level for diabetes, if you have been diagnosed with prediabetes or diabetes already & whether you’re at your A1C target, etc.

If you are living with diabetes already, you likely have your A1C checked between 2-4 times per year; less often if you are at or under your target and more often if you are not at your target. However, your diabetes management team will individualize your frequency based on your specific situation.

If you have not been diagnosed with diabetes and are considered low-risk, you may go years between tests unless your risk factors change.

If you have not been diagnosed yet and are considered high-risk, you may have tests 1-2 times per year to monitor any changes.

If you’re 40 or older, you can use the Canadian Diabetes Risk Questionnaire (CANRISK) online to determine your risk for developing pre-diabetes or type 2 diabetes. If you’re under 40, this tool may still be applicable. In either case, always speak to your healthcare provider for personalized evaluation and advice.

As mentioned, there are a lot of variables that can influence the frequency of your testing so be sure to consult your health care team if you have questions.

How does A1C get measured?

A1C is most often measured by blood draw in a lab. Here in Cape Breton, you’ll need a blood work requisition form from a provider and will need to book a blood draw appointment at one of the hospitals, or have someone come to your home. Your doctor, nurse practitioner, pharmacy, and/or diabetes clinic will be able to see these results afterward, generally in the next few days. Try to have it done at least 2 weeks prior to your doctor or clinic appointment, in case of delays.

In some places, you may be able to have a Point-of-Care A1C completed. For example, my local Shoppers Drug Mart Primary Care Clinic provides this test on-site. You will need to book an appointment at the clinic for this test and the test will be ready within approximately 20 minutes. You can read more about this service here.

Do I need to fast before having my A1C checked?

You do not! Remember, it’s an average over a longer period of time so fasting prior to the test will not impact your results. Eat as you normally would.

What should my A1C be?

It depends on a few factors and may change over time!

Age, type of diabetes, results of other bloodwork tests, other health conditions and more can affect what your individual target should be and your health care team will communicate this to you.

Keep in mind: Canadian guidelines target & diagnosis numbers vary slightly from some other countries, so you may see different numbers online.

Note: While diagnosis of prediabetes often includes A1C of 6.0-6.4%, there may still be some risk associated with A1C levels below 6.0%.

In some cases, your A1C results may be 5.5-5.9% but other bloodwork falls outside of target range and your healthcare provider may communicate a diagnosis or elevated risk to you.

If you have already been diagnosed with diabetes, you may see targets such as these from Diabetes Canada:

Pediatrics will also have more individualized targets than the above chart, so keep this in mind.

I often see clients who are confused why Aunt Sue has a different A1C target than they do and may feel distressed that they can’t get to the same place. There may be context missing from why someone’s target is different than yours, or why it seems easier for them to get or stay within target.

Your healthcare team and diabetes clinic are there to support you. Ask about in-person and online resources that are available, whether you’re caring for yourself or someone else.

Long story short, there are different numbers for different people in different situations. If you have questions, speak to your primary healthcare provider or diabetes team.

Is A1C the most important number for diabetes?

Arguably, no. It is rare that health ever comes down to just one test, number, or measurement.

Your healthcare team will evaluate numbers such as your fasting glucose, random glucose, time in range (if you wear a CGM sensor), kidney function, thyroid, and all sorts of other things when it comes to managing your diabetes.

They will also look at non-quantitative things such as your quality of life, stress levels, smoking or alcohol use, food intake, physical activity, and all sorts of other things.

How do I compare A1C with the blood glucose readings I take with a glucometer or CGM?

This handy table from MyHealth Alberta may explain better:

In most cases, we want our fasting blood sugar to be between 4-7mmol/L and post-meal blood sugar between 5-10mmol/L..

You can see how the readings that you measure day-to-day can influence your A1C over time, even if you are within range. You may spend more time at the high-end than mid-or-low range, or have higher blood sugar at times where you don’t check & aren’t aware of. We’ll cover more about this in a future post.

So, let’s sum it up!

In the end, it’s important to understand the benefits of knowing your A1C in terms of diabetes risk and management, but also its limitations in terms of what it can tell you in regards to your risk and management.

As always, if you have questions or are interested in how we can help you manage your risk or your diabetes, reach out!