What’s an A1C Test?

If you live with any form of diabetes, you’ve probably heard of an A1C test. If not, that’s okay, too—everyone learns different things about diabetes at different times.

What is an A1C test?

The A1C test is a blood test that helps you and your healthcare provider see how well your diabetes management plan is working. People with type 1 and type 2 diabetes  will have this test performed. It shows your average blood sugar (glucose) over the past two to three months as a percentage. And yes, it’s still a relevant metric, despite advancements in medications, technology and the importance of time-in-range data.

You might have heard it called:

• Hemoglobin A1C
• HbA1C
• Or glycated hemoglobin

These are usually medical terms your healthcare provider will throw around or what you might see on your lab results after your regular checkups, but most people living with diabetes just call it A1C.

What does an A1C test show?

When sugar enters your blood, it sticks to a protein in your red blood cells. This creates something called “glycated hemoglobin.” The more sugar in your blood, the higher your A1C number.

Checking your blood sugar daily is important While monitoring your sugar levels is important in daily self-care, including the A1C test gives you a more complete picture of your glucose management. Checking your blood sugar reflects a specific point in time, while an A1C measures a longer period of time. Advantages of A1C testing include not being affected by what you eat or drink (or if you eat or drink at all), stress or illness or recent physical activity before the test. On the other hand, your regular glucose measurements are affected by all of these factors.  

What do these numbers mean?

For most people, your A1C is a three-month average. Higher numbers mean more sugar in your blood, which over time may raise your risk of complications from diabetes. Most healthcare providers look at A1C levels in a range to determine diabetes risk and treatment plans. These  different A1C levels and ranges tell you different things, especially if you’ve been recently diagnosed or have lived with diabetes for some time.

For an initial diabetes diagnosis here’s what these ranges mean:

• 5.6 or less: Normal. A person with this A1C does not have diabetes or does not show any risk of developing diabetes in the near future.  
• 5.7–6.4: Pre-diabetes. This A1C level is a warning that someone may develop type 2 or have the beginning onset of type 1 diabetes. 
• 6.5 or higher: Diabetes. An A1C of this level is when diabetes is diagnosed.

If you’re living with diabetes, here’s what the ranges mean for you:

• 6.5 or less: This is an A1C goal for people with diabetes but  without complex health needs and functional limitations, few treatment concerns, risks and care burden.
• 7 or less: This is the target A1C range for most adults and children diagnosed with diabetes, which may vary depending on individual circumstances and healthcare provider recommendations. It is essential to consult your healthcare team to determine the specific A1C goal that is right for you. 
• 7–7.5: A1C goal for older adults who are generally without complex health concerns.
• 8 or less: A1C goal for older adults with complex and increased health concerns.
• No A1C goal: This is generally for older adults with very complex and advanced health concerns and adults with limited life expectancy.

The key takeaway is that A1c should be individualized and a person’s goal A1c is correlated with the length of time they have lived with diabetes and health status.

What affects A1C results?

Like many things in life with diabetes, almost everything and anything can impact your A1C. Here are some specific factors that may influence your results.

A few things can make your A1C test less accurate:

• You’ve lost a lot of blood
• You had a blood transfusion
• You’re low in iron
• You’re pregnant or had a baby within last three months
• You live wit kidney or liver disease or HIV
• You  live with a different type of hemoglobin (hemoglobin variant), like sickle cell trait, which is common in Black, Mediterranean and Southeast Asian communities
• Even switching to a new lab can slightly change your results

How to translate your A1C to an average blood sugar level

Depending on your A1C results, your average blood sugar level might be:

• 5%—5.4 mmol/L97 mg/dL
• 6%—7.0 mmol/L126 mg/dL
• 7%—8.6 mmol/L154 mg/dL
• 8%—10.2 mmol/L183 mg/dL
• 9%—11.8 mmol/L212 mg/dL
• 10%—13.3 mmol/L240 mg/dL
• 11%—14.9 mmol/L269 mg/dL
• 12%—16.6 mmol/L298 mg/dL
• 13%—18.1 mmol/L326 mg/dL
• 14%—19.7 mmol/L355 mg/dL

If you monitor your glucose r levels with a continuous glucose monitor (CGM), visiting your healthcare provider can feel less surprising because current CGMs typically provide predictions through a little something called a glucose management indicator (GMI). While they are not always 100% accurate, they offer a good starting point that is usually close to your actual levels. 

How are A1C, time-in-range and GMI related?

A GMI is an estimate of your A1C, but it’s not an official number from your healthcare provider. Only your A1C accurately reflects your average blood sugar over the past two to three months. Most healthcare providers do not use your GMI to make decisions about your blood sugar or change your routine. It’s helpful, but most clinics still rely on your A1C results.

Knowing your time-in-range, GMI and A1C can give your healthcare providers a complete picture of your blood sugar. However, how they support your care depends on their clinic’s rules. 

Time-in-range tells you how often you’ve been in your target blood sugar range. For example, if your target range is 70 to 180 mg/dL, your CGM might tell you that you’ve been 70% in range over the past three, seven, 14, 30 or 90 days.

Sometimes, time-in-range is a more helpful metric for healthcare providers to understand, because A1C is just an average of your blood sugar readings. A1C can’t determine if you have periods of highs and lows (AKA glucose excursions). So, you might still get an A1C result that meets your goals even if you’re having periods of highs and lows. 

Is there really a “good” or “bad” A1C?

Nope! The A1C is just a number. It’s giving you and your healthcare team a measurement to base decisions off of.  If the A1C is above targets set by your healthcare provider, that’s okay. It just means some adjustments to your diabetes management plan need to be made.  

What matters is working with your care team to stay as healthy as possible and living a life with diabetes that you feel good about.