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Hemoglobin A1c (HbA1c) by High-Performance Liquid Chromatography (HPLC)

Published: August 9, 2026Updated: August 16, 2026

This test measures the percentage of hemoglobin that is coated with sugar (glycated hemoglobin), reflecting your average blood sugar levels over the past 2–3 months.

Quick summary

["HbA1c helps doctors track long-term diabetes control and adjust treatment plans."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
717-9
Short code
Hgb Bld Ql
Synonyms
Hgb Bld Ql
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
12
Ref high
17.5
Critical range
7 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85018
SNOMED
900000000000003004
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Is HbA1c Used For?

HbA1c is primarily used to diagnose diabetes and monitor how well your blood sugar is managed over time. It’s a key tool for assessing whether your current treatment plan is effective and identifying if your blood sugar levels are consistently high or low.

How Is HbA1c Different from Fasting Blood Sugar?

Unlike a single blood sugar test (e.g., fasting glucose), HbA1c gives a broader picture of your average glucose levels, accounting for daily fluctuations. It’s less affected by short-term stress or meals, making it a more reliable long-term indicator.

How Is HbA1c Tested?

This test uses a blood sample drawn from your arm and analyzed via high-performance liquid chromatography (HPLC) to separate and measure glycated hemoglobin. Results are expressed as a percentage (e.g., 5.7% or 6.2%).

What Do HbA1c Results Mean?

Results are typically reported as a percentage. While exact ranges vary by lab, common thresholds include: below 5.7% (normal), 5.7–6.4% (prediabetes), and 6.5% or higher (diabetes). Your doctor will interpret results in the context of your overall health.

Reference range

Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A

Specimen: whole-blood

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: HbA1c in Diabetes Management

Short name

HbA1c

Frequently asked questions

Why might my doctor order an HbA1c test?
Your doctor may recommend an HbA1c test if you have symptoms of high blood sugar (e.g., frequent urination, excessive thirst), a family history of diabetes, or if you’re at risk due to weight, age, or other health conditions. It’s also used annually for people with diabetes to check progress with treatment.
What happens if my HbA1c is high?
A high HbA1c suggests your blood sugar has been consistently elevated, which can damage blood vessels and organs over time. Treatment may include lifestyle changes (diet, exercise), medications, or insulin to lower blood sugar and improve long-term health.
How often should I get an HbA1c test?
Typically, people with diabetes get HbA1c tests every 3–6 months to track progress. Your doctor may adjust frequency based on your specific needs, such as more frequent checks if your blood sugar is poorly controlled.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy