HbA1c Explained: What It Means and What Is a Good Level?

Written by Dr.Albana Greca, MD, MMedSc
Medically reviewed by Dr.Ruden Cakoni, MD, Endocrinologist

Last reviewed May 2026

HbA1c is one of the most important blood tests used to understand long-term blood sugar control. While a finger-prick blood sugar test shows your glucose level at one moment, HbA1c gives a wider picture of your average blood sugar over the past 2 to 3 months.

This makes HbA1c very useful for people with diabetes, prediabetes, insulin resistance, or anyone trying to understand whether their blood sugar is staying in a healthy range over time.

On this page, you will learn what HbA1c means, what a good A1c level may be, how it compares with daily blood sugar readings, and how to convert HbA1c into estimated average glucose.


What Is HbA1c?

HbA1c, also called A1c or glycated hemoglobin, is a blood test that measures how much glucose is attached to hemoglobin inside red blood cells.

Hemoglobin is the protein in red blood cells that carries oxygen. When glucose circulates in the blood, some of it attaches to hemoglobin. The more glucose there is in the bloodstream over time, the higher the HbA1c result may become.

Because red blood cells live for about 2 to 3 months, HbA1c reflects your average blood sugar over that period.

In simple words:

HbA1c tells you how your blood sugar has been behaving over time — not just today.


Why HbA1c Matters?

HbA1c matters because blood sugar can change from hour to hour. It may rise after meals, fall after activity, change with stress, sleep, illness, medication, and many other factors.

A single blood sugar reading can be useful, but it does not always show the full picture.

HbA1c helps answer questions such as:

  • Has my blood sugar been high for several weeks?
  • Is my diabetes treatment working?
  • Am I at risk of diabetes complications?
  • Is my prediabetes improving or getting worse?
  • Do my daily glucose readings match my long-term control?

For many people, HbA1c is used together with fasting glucose, after-meal glucose, and sometimes continuous glucose monitoring.


What Is a Good HbA1c Level?

A “good” HbA1c level depends on your age, health condition, diabetes type, risk of low blood sugar, medications, pregnancy status, and your doctor’s advice.

For many adults with type 2 diabetes, a commonly used target is around 7% or lower, but this is not the right goal for everyone.

Some people may need a stricter target. Others may need a safer, more flexible target, especially if they are older, have heart disease, kidney disease, frequent hypoglycemia, or other serious health problems.

General interpretation often looks like this:


HbA1c Result What It May Suggest
Below 5.7% Usually considered normal
5.7% to 6.4% Prediabetes range
6.5% or higher Diabetes range, if confirmed
Around 7% Common treatment target for many adults with diabetes
Above target May suggest blood sugar is too high over time

References: CDC: A1C Test for Diabetes and Prediabetes; American Diabetes Association: Understanding A1C Test.


For more detail, read Good A1c Level for Type 2 Diabetes.

HbA1c vs Blood Sugar: What Is the Difference?


HbA1c and blood sugar are related, but they are not the same.

A blood sugar test tells you your glucose level at a specific moment. For example, your fasting blood sugar in the morning or your blood sugar 2 hours after eating.

HbA1c gives an average picture over several weeks.

This means you can have:

  • A normal fasting blood sugar but a higher HbA1c
  • A high after-meal blood sugar but an acceptable HbA1c
  • Daily glucose swings that HbA1c does not fully show
  • A good HbA1c but frequent low or high readings

That is why both numbers can be useful.

For a full explanation, read A1c vs Blood Sugar: What’s the Difference?


How Is HbA1c Calculated?

HbA1c is measured in a laboratory using a blood sample. It is reported as a percentage.

The percentage shows how much hemoglobin has glucose attached to it.

For example, an HbA1c of 7% means that about 7% of hemoglobin is glycated.

Doctors may also use something called estimated average glucose, or eAG. This converts HbA1c into an average blood glucose number, usually shown in mg/dL or mmol/L.

This can make the result easier to understand because many people are already familiar with daily blood sugar readings.

For more detail, read: How A1c Is Calculated and What eAG Means.


HbA1c to Average Glucose Conversion

HbA1c can be converted into estimated average glucose, often called eAG.

This helps answer a common question:

“What does my A1c mean in daily blood sugar numbers?”

Some examples include:


HbA1c Estimated Average Glucose
5.7% About 117 mg/dL
6.0% About 126 mg/dL
6.5% About 140 mg/dL
7.0% About 154 mg/dL
8.0% About 183 mg/dL
9.0% About 212 mg/dL
10.0% About 240 mg/dL

Reference: Estimated average glucose values are commonly calculated from HbA1c using the ADAG/eAG formula used by the American Diabetes Association.


These numbers are estimates. Your actual daily glucose readings may vary, especially if you have large spikes after meals or episodes of low blood sugar.

You can start using our calculator here: HbA1c to Average Glucose Calculator.

What Does A1c 5.6 Mean?

An HbA1c of 5.6% is usually just below the prediabetes range. Prediabetes is commonly defined as HbA1c from 5.7% to 6.4%.

However, an A1c of 5.6% may still be worth paying attention to, especially if you have risk factors such as:

  • Family history of type 2 diabetes
  • Overweight or abdominal weight gain
  • High blood pressure
  • High triglycerides
  • Polycystic ovary syndrome
  • Sedentary lifestyle
  • Previous gestational diabetes

A single result should not be interpreted alone. Your doctor may also look at fasting glucose, symptoms, weight, blood pressure, cholesterol, and your overall risk profile.

Read more here on A1c 5.6: Is It Prediabetes? What It Means


Fasting Glucose vs HbA1c: Which Matters More?


Fasting glucose and HbA1c measure different things.

Fasting glucose shows your blood sugar after not eating for at least 8 hours. HbA1c shows your average blood sugar over several weeks. Both can matter.



Sometimes fasting glucose and HbA1c do not match perfectly. When this happens, your doctor may repeat tests or use additional information.

Read more here on Fasting Glucose vs A1c: Which Matters More?
fasting glucose vs a1c

When Should You Talk to Your Doctor?

You should speak with your doctor if:

  • Your HbA1c is above your personal target
  • Your A1c is rising over time
  • Your fasting glucose is often high
  • Your blood sugar is high after meals
  • You have frequent low blood sugar episodes
  • Your home glucose readings do not match your HbA1c
  • You are pregnant or planning pregnancy
  • You have symptoms such as excessive thirst, frequent urination, unexplained weight loss, fatigue, or blurred vision

Do not change diabetes medication, insulin doses, or treatment targets without medical advice.

HbA1c is helpful, but it is only one part of your health picture.


Key Takeaways


HbA1c is a blood test that shows your average blood sugar over the past 2 to 3 months.

A good HbA1c level depends on your personal health situation and should be discussed with your doctor.

HbA1c is different from daily blood sugar readings. Both can be useful.

Estimated average glucose, or eAG, helps convert HbA1c into a number that looks more like daily blood sugar readings.

If your HbA1c is above target, repeated high readings are more important than one single result.


Medical Disclaimer

This page is for educational purposes only and does not replace medical advice, diagnosis, or treatment. Always speak with your doctor or qualified healthcare professional about your personal blood sugar targets, HbA1c results, medication, and treatment plan.

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