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Hemoglobin A1c (HbA1c) measured by high-performance liquid chromatography (HPLC) in whole blood

Published: August 9, 2026Updated: August 17, 2026

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

Quick summary

["HbA1c helps doctors assess long-term blood sugar control in people with diabetes or prediabetes."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
104877-6
Short code
Hct 1.5h p Glc VFr Bld
Synonyms
Hct 1.5h p Glc VFr Bld
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
36
Ref high
50
Critical range
18 N/A – 60 N/A
Fasting
true
Population
adult
Sex
all
Age range
18–65 years
CPT
85014
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why is HbA1c important?

HbA1c provides a snapshot of your blood sugar management over time, unlike daily glucose checks. It’s a key tool for doctors to adjust diabetes treatments and prevent complications like nerve damage or kidney disease.

How is HbA1c different from daily blood sugar tests?

Unlike fingerstick glucose tests (which show your blood sugar at a single moment), HbA1c averages your glucose levels over months. It’s less affected by short-term stress or activity spikes.

What does an HbA1c result mean?

Results are typically reported as a percentage (e.g., 5.7%–6.4% may indicate prediabetes; 6.5% or higher often signals diabetes). While guidelines use these ranges, your doctor will interpret results based on your health goals and history.

Who might need an HbA1c test?

Doctors recommend HbA1c testing for people with diabetes, those with prediabetes (high risk), or anyone with symptoms like frequent thirst, fatigue, or unexplained weight changes. It’s also part of routine check-ups for high-risk groups.

Reference range

Adult males: 38-50%; Females: 36-44%N/A

Specimen: serum

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.

◆Associated findings1

Short name

HbA1c

Frequently asked questions

What does an HbA1c test involve?
A small blood sample is taken from your arm (like a routine blood draw). The sample is analyzed using HPLC to measure the percentage of hemoglobin bound to sugar. Results are usually ready within 24–48 hours.
How often should I get an HbA1c test?
Typically, people with diabetes check HbA1c every 3–6 months. Your doctor may adjust frequency based on your blood sugar goals, treatment plan, or risk factors.
Can diet or exercise affect HbA1c results?
Yes! Healthy eating and regular physical activity can lower HbA1c levels. However, results reflect your average glucose over months, so short-term changes (like a meal or workout) may not immediately alter the test result.
  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 17, 2026. · Read our editorial policy