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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, 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
4627-6
Short code
Hgb Yoshiz Bld Ql
Synonyms
Hgb Yoshiz 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 HbA1c Test Measures

HbA1c represents the proportion of hemoglobin molecules linked to glucose (glycated hemoglobin). It’s a key indicator of how well your blood sugar has been managed over time, accounting for daily fluctuations that individual blood sugar tests can’t capture.

Why It Matters for Diabetes Management

Unlike daily blood sugar checks, HbA1c provides a broader picture of your metabolic health. It’s used to diagnose diabetes, monitor treatment effectiveness, and prevent complications like nerve damage or kidney disease.

How the Test Works

Your blood sample is analyzed using HPLC, which separates hemoglobin types based on their sugar content. The test detects the percentage of HbA1c among all hemoglobin molecules.

What to Expect Before the Test

No special preparation is needed. A small blood sample is drawn from your arm, similar to other blood tests. If you’re pregnant or have a clotting disorder, let your doctor know.

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.

◆Associated findings1

Short name

HbA1c

Frequently asked questions

How often should I get an HbA1c test?
Typically, adults with diabetes are tested every 2–3 months to adjust medications. Your doctor may recommend more frequent checks if your blood sugar is unstable or if you’re pregnant.
Can fasting affect HbA1c results?
No, HbA1c reflects average blood sugar over months, so fasting isn’t required. It’s not influenced by short-term eating habits.
What do HbA1c levels below 6.5% mean?
An HbA1c below 6.5% suggests excellent long-term blood sugar control, often considered safe for people without diabetes. However, your doctor will interpret results based on your overall health and goals.
  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