Medical Disclaimer: This article is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about diabetes management, medication changes, or treatment plans.

What Is A1C? Understanding Your Average Blood Sugar

Creator: Editorial Team
Published: 2026-03-28

Last updated: March 2026 | Reviewed by MDTalks Editorial Team

The A1C test is one of the most important numbers in diabetes care. Unlike a fingerstick glucose reading that captures a single moment, the A1C provides a picture of your average blood sugar over the past two to three months. Whether you have been diagnosed with diabetes, have prediabetes, or are at risk, understanding what A1C means and how to interpret your results is fundamental to managing your health.

How the A1C Test Works

Hemoglobin is a protein inside red blood cells that carries oxygen. When glucose circulates in the bloodstream, some of it attaches to hemoglobin, forming glycated hemoglobin, or HbA1c. The higher your blood sugar has been over the past two to three months, the more glucose is bound to hemoglobin.

Because red blood cells live for approximately 120 days, the A1C test reflects a weighted average of blood glucose over that lifespan, with more recent weeks having a greater influence on the result.

The test requires a blood sample, usually drawn from a vein. It does not require fasting. Results should come from a laboratory certified by the National Glycohemoglobin Standardization Program (NGSP) for accuracy. Point-of-care tests in a doctor’s office can be useful for monitoring but should not be used alone for diagnosis, according to ADA guidelines.

A1C Ranges: What Your Number Means

A1C Result	Interpretation	Estimated Average Glucose (eAG)
Below 5.7%	Normal	Below 117 mg/dL
5.7% to 6.4%	Prediabetes	117–137 mg/dL
6.5% or higher	Diabetes	140 mg/dL or higher

An A1C of 6.5% or higher on two separate tests is diagnostic for diabetes. A single test result of 6.5% or higher combined with symptoms of diabetes (excessive thirst, frequent urination, unexplained weight loss) may also be sufficient for diagnosis.

Estimated Average Glucose (eAG)

Many labs now report an estimated average glucose alongside the A1C percentage. This conversion helps patients relate their A1C to the daily glucose numbers they see on their meter or CGM. The general formula: eAG (mg/dL) = (28.7 x A1C) - 46.7.

A1C (%)	eAG (mg/dL)
5.0	97
6.0	126
7.0	154
8.0	183
9.0	212
10.0	240

A1C Targets: What to Aim For

The ADA recommends a general A1C target of below 7% for most nonpregnant adults with diabetes. However, targets should be individualized. Your healthcare provider may set a different target based on:

Age: Older adults or those with limited life expectancy may have a less aggressive target (below 8%).
Hypoglycemia risk: Patients prone to low blood sugar episodes may benefit from a higher target.
Duration of diabetes: Newly diagnosed patients may aim for tighter control to take advantage of the “legacy effect” of early intensive management.
Comorbidities: The presence of cardiovascular disease, kidney disease, or other conditions influences target setting.
Pregnancy: Pregnant women with pre-existing diabetes have stricter targets (generally below 6.5% if achievable without excessive hypoglycemia).

For children and adolescents with type 1 diabetes, the ADA recommends an A1C below 7.5%. See Diabetes in Children: What Parents Need to Know.

How Often Should You Get Tested?

The ADA recommends:

Twice a year for patients who are meeting treatment goals and have stable glycemic control
At least four times a year for patients whose therapy has changed or who are not meeting targets

Your provider may also order an A1C test if you have risk factors for diabetes or prediabetes, even without a prior diagnosis. The CDC recommends that all adults aged 35 and older be screened for prediabetes and type 2 diabetes.

For guidance on daily monitoring, see Blood Sugar Monitoring: How Often and When to Test.

Factors That Can Affect A1C Accuracy

The A1C test is highly reliable, but certain conditions can affect results:

Hemoglobin variants: Sickle cell trait, thalassemia, and other hemoglobinopathies can interfere with some A1C assays. NGSP-certified labs use methods that minimize this interference, but alternative testing (fructosamine, glycated albumin) may be needed.
Anemia and blood loss: Conditions that shorten red blood cell lifespan (hemolytic anemia, significant blood loss) can falsely lower A1C. Iron-deficiency anemia may falsely raise it.
Kidney disease: Advanced chronic kidney disease can affect A1C accuracy.
Pregnancy: Hemodilution in pregnancy can lower A1C, making it less reliable for gestational diabetes diagnosis. The oral glucose tolerance test is preferred. See Gestational Diabetes: Diagnosis and Management.
Recent blood transfusion: Can temporarily affect results.

If your A1C result does not match your daily glucose readings or CGM data, discuss potential interfering factors with your provider.

A1C vs. Daily Glucose Monitoring vs. CGM

Each measurement provides different information:

Measurement	What It Shows	Time Frame	Best For
A1C	Average glucose	2–3 months	Long-term trend assessment
Fingerstick glucose	Single-point reading	That moment	Pre-meal, pre-exercise checks
CGM	Continuous glucose trend	Real-time + historical	Pattern recognition, time in range

Time in range (TIR) is an increasingly important metric from CGM data. It measures the percentage of time glucose stays within the target range of 70 to 180 mg/dL. A TIR of 70% or higher roughly corresponds to an A1C below 7%.

CGM and A1C are complementary, not interchangeable. A1C captures the average but misses variability. A person with an A1C of 7% might have stable glucose throughout the day or might experience frequent highs and lows that average out. CGM reveals those patterns.

Learn more about monitoring technology in CGM Devices Compared: Dexcom, Libre, and Medtronic.

How to Lower Your A1C

Reducing A1C requires a sustained approach that combines medication adherence, dietary management, physical activity, and regular monitoring. Evidence-based strategies include:

Take medications as prescribed. Metformin alone can reduce A1C by 1% to 1.5%. GLP-1 receptor agonists and SGLT2 inhibitors offer additional reductions with cardiovascular and weight benefits.
Reduce refined carbohydrates. Replacing processed carbs with whole grains, vegetables, and lean protein directly impacts post-meal glucose spikes.
Exercise regularly. At least 150 minutes per week of moderate activity. Exercise improves insulin sensitivity for up to 72 hours after a session.
Lose weight if overweight. Even a 5% to 7% weight loss can meaningfully improve A1C and insulin sensitivity.
Monitor consistently. Regular glucose checks or CGM use help identify patterns that inform treatment adjustments.
Manage stress and sleep. Both chronic stress and poor sleep raise blood sugar through hormonal pathways.

For a comprehensive management approach, see the Complete Guide to Diabetes Management in 2026.

Key Takeaways

The A1C test measures average blood sugar over two to three months and is the primary tool for diagnosing and monitoring diabetes.
Normal A1C is below 5.7%; prediabetes is 5.7% to 6.4%; diabetes is 6.5% or higher.
The standard A1C target for most adults with diabetes is below 7%, but targets should be individualized with your healthcare provider.
A1C testing should occur at least twice a year for stable patients and quarterly for those adjusting treatment.
Certain conditions (hemoglobin variants, anemia, pregnancy) can affect A1C accuracy — discuss discrepancies with your provider.
Consult your healthcare provider to set appropriate A1C targets and to develop a plan for reaching them.

Sources

American Diabetes Association. “Understanding A1C.” diabetes.org
National Institute of Diabetes and Digestive and Kidney Diseases. “The A1C Test & Diabetes.” niddk.nih.gov
Centers for Disease Control and Prevention. “A1C Test for Diabetes and Prediabetes.” cdc.gov
American Diabetes Association. “Standards of Care in Diabetes — 2026.” Diabetes Care, January 2026.

This article is part of the MDTalks Diabetes Hub. For AI-assisted comparisons, see AI Answers About Diabetes.

Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider for personalized diabetes management guidance.