HbA1c Normal Range: What Your A1C Result Means

HbA1c (also called A1C or glycated hemoglobin) measures the percentage of hemoglobin in red blood cells that has glucose attached to it, giving doctors a picture of average blood sugar over time rather than a single moment.

Quick Answer

For most adults who aren't pregnant, an HbA1c below 5.7% is generally considered normal, 5.7%–6.4% is the range commonly classified as prediabetes, and 6.5% or higher is the threshold used to diagnose diabetes. These are diagnostic categories, not universal treatment targets — and an abnormal result is often confirmed with a repeat test or additional testing rather than treated as final on its own. A doctor interprets your specific result alongside your health history and other test results.

What Is HbA1c?

As red blood cells circulate, some of the glucose in the blood attaches to the hemoglobin inside them — this is what HbA1c measures. Because red blood cells last for a few months before being replaced, the result reflects a weighted average of blood sugar over roughly the past two to three months, with more recent weeks contributing more than months further back — rather than one single, literal "3-month average."

This is different from a fingerstick or lab glucose reading, which reflects blood sugar at one specific moment and can swing significantly with meals, activity, stress, or illness. HbA1c is used both to help diagnose prediabetes and diabetes, and — for people already diagnosed — to monitor how well treatment is working over time. See our diabetes blood tests guide for how it compares to other tests, and our HbA1c lab test page for test-specific details.

HbA1c Normal Range

These are diagnostic categories used to help identify prediabetes and diabetes, not personalized treatment targets. A result in the diabetes range is usually confirmed with a repeat test on a different day, unless blood sugar is very high or classic symptoms of high blood sugar are already present — in which case a doctor may not need to repeat the test. See "HbA1c Treatment Targets" below for how targets differ once diabetes is diagnosed.

HbA1c Levels Chart

HbA1c can also be expressed as an estimated average glucose (eAG), which translates the percentage into the same mg/dL or mmol/L units used for everyday glucose readings — though this is an estimate, not a literal one-to-one reading, since the actual average blood sugar behind any single HbA1c number can vary meaningfully between individuals.

eAG is calculated from the HbA1c result using a standard formula, not measured directly — it's useful for relating HbA1c to glucose numbers you may already be familiar with, but it doesn't replace your actual glucose readings, and a doctor shouldn't estimate your day-to-day blood sugar from eAG alone, since the real range behind any single HbA1c value is broad.

What Does Your HbA1c Result Mean?

A few examples of how results are generally categorized (not a diagnosis of any individual reader):

• HbA1c 5.0%: within the range commonly classified as normal.
• HbA1c 5.5%: within the range commonly classified as normal, though closer to the upper end.
• HbA1c 5.7%: at the lower edge of the range commonly classified as prediabetes.
• HbA1c 6.0%: within the range commonly classified as prediabetes.
• HbA1c 6.4%: at the upper edge of the range commonly classified as prediabetes.
• HbA1c 6.5%: at the threshold commonly used to diagnose diabetes, usually alongside a repeat test or additional confirmation.
• Higher results: generally reflect higher average blood sugar, and a doctor evaluates them alongside your symptoms, other test results, and overall health.

None of these examples diagnoses any individual — the same number can mean something different depending on a person's full clinical picture, and a doctor should always interpret your specific result.

HbA1c and Prediabetes

Prediabetes means blood sugar is higher than normal but not yet in the diabetes range. It doesn't mean diabetes is inevitable — many people with prediabetes can lower their risk of progressing to diabetes through lifestyle changes, and some return to the normal range over time. It does, however, mean a higher-than-average risk, which is why doctors often recommend follow-up testing and some of the same lifestyle measures used to manage diabetes. Our prediabetes guide and our can prediabetes be reversed guide cover this in more depth.

HbA1c and Diabetes

An HbA1c of 6.5% or higher is the threshold commonly used to diagnose diabetes, usually confirmed with a repeat test on a different day unless blood sugar is very high or classic symptoms (such as excessive thirst, frequent urination, or unexplained weight loss) are already present. Once diabetes is diagnosed, HbA1c is also used to monitor how well treatment is working over time — but the number used for ongoing monitoring is interpreted differently from the number used for diagnosis, which is the focus of the next section.

HbA1c Treatment Targets

This is an important distinction: the diagnostic ranges above are not the same as a personal treatment target.

For someone already diagnosed with diabetes, the HbA1c a doctor aims for is individualized rather than a single universal number for everyone. It can depend on:

• Age
• How long diabetes has been present
• Risk of hypoglycemia (low blood sugar) from treatment
• Other health conditions
• Pregnancy
• Current medications
• Individual clinical circumstances and preferences

This guide doesn't state a universal target, because there isn't one — your doctor sets a personal goal based on your specific situation, which may be different from someone else's goal even with a similar diagnosis.

How Often Should HbA1c Be Checked?

Testing frequency also depends on individual circumstances rather than one fixed schedule. As a general guideline, people with diabetes who are meeting their treatment goals and have stable blood sugar are often tested about twice a year, while testing is often done quarterly (about every three months) if treatment has recently changed or blood sugar isn't at the current goal. Pregnancy and other specific clinical situations can also change how often testing is appropriate. Your doctor determines the right interval for you.

HbA1c vs Blood Glucose

Both are useful, and for people with diabetes, day-to-day glucose monitoring and periodic HbA1c testing generally serve different, complementary purposes rather than replacing one another.

Does HbA1c Require Fasting?

No — HbA1c itself doesn't require fasting, since it reflects an average over time rather than your blood sugar at that moment, and eating beforehand doesn't meaningfully change the result. That said, if your doctor orders other blood tests at the same visit — such as a fasting glucose or a lipid panel — those specific tests may have their own separate fasting requirements, so it's worth checking what else is being tested rather than assuming HbA1c's own lack of a fasting requirement applies to the whole blood draw.

What Can Affect HbA1c Accuracy?

HbA1c relies on the behavior of red blood cells, so conditions that affect those cells can make the result less accurate as a reflection of true average blood sugar. Recognized factors include:

• Certain types of anemia
• Hemoglobin variants (such as sickle cell trait or disease, and thalassemia)
• Conditions that shorten or lengthen red blood cell lifespan
• Recent significant blood loss or a blood transfusion
• Kidney disease
• Pregnancy
• Certain medications and other underlying conditions

If any of these apply to you, it's worth mentioning to your doctor, since they may rely more on fasting glucose or an oral glucose tolerance test instead, or interpret your HbA1c result differently. Our diabetes blood tests guide compares these alternative tests.

HbA1c During Pregnancy

Pregnancy changes how glucose testing is approached. HbA1c may sometimes be used early in pregnancy to check for diabetes that was already present but undiagnosed before pregnancy began. However, it isn't the standard test for gestational diabetes itself — a glucose challenge test or an oral glucose tolerance test, usually done between 24 and 28 weeks of pregnancy, is the standard approach for that. This guide doesn't provide pregnancy-specific HbA1c diagnostic thresholds, since testing and interpretation during pregnancy follow a different process best guided directly by your prenatal care team. See our gestational diabetes guide for more detail.

How to Lower HbA1c

For people whose HbA1c is higher than their goal, approaches with strong evidence behind them generally include:

• A generally healthy, consistent eating pattern
• Regular physical activity
• Weight management, when appropriate and recommended by a doctor
• Taking prescribed medication as directed, and not adjusting it yourself
• Glucose monitoring, when your doctor recommends it, to understand your own patterns
• Attention to sleep and stress, which can both affect blood sugar

There's no strong evidence that supplements can reliably lower HbA1c or replace prescribed treatment, so this guide doesn't recommend any. Our best foods for diabetes and diabetes and exercise guides cover specific, evidence-supported lifestyle measures in more depth.

When Should You Talk to a Doctor?

It's worth contacting a doctor if:

• You receive an unexpectedly high HbA1c result
• Your result falls in the prediabetes or diabetes range for the first time
• Your result has changed significantly from a previous test
• You have symptoms of significantly high blood sugar, such as excessive thirst, frequent urination, blurred vision, or unexplained weight loss
• You already have diabetes and your results are getting worse despite following your treatment plan

A single result rarely tells the whole story — your doctor interprets it alongside your health history, symptoms, and other test results.

Sources

• A1C — MedlinePlus
• Estimated Average Glucose (eAG) — MedlinePlus
• A1C Test for Diabetes and Prediabetes — CDC
• Diabetes Diagnosis & Tests — American Diabetes Association
• The A1C Test & Diabetes — NIDDK