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Serum or Plasma Hemoglobin A1c (Glycated Hemoglobin) by High-Performance Liquid Chromatography (HPLC)

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

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

Quick summary

["Helps track long-term diabetes control and blood sugar management."]

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

Key facts at a glance

LOINC
6636-5
Short code
FLUAV Pt Chal Ab Ser HAI-aCnc
Synonyms
FLUAV Pt Chal Ab Ser HAI-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0.8
Ref high
1.2
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
hai
CPT
85610
SNOMED
396252006
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

What This Test Measures

HbA1c reflects how well your blood sugar has been controlled over time. It’s a stable form of hemoglobin that remains in red blood cells for about 120 days, giving a snapshot of your average glucose levels during that period.

Why It’s Done

Doctors use HbA1c to diagnose diabetes, monitor treatment progress, and assess long-term blood sugar management in people with diabetes or prediabetes.

How It’s Done

A small blood sample is taken from your arm and sent to a lab. The sample is analyzed using HPLC to separate and measure the proportion of glycated hemoglobin.

What to Expect Before or After

No special preparation is needed, but fasting is not required. Results may take a few days to arrive. If you’re pregnant or have certain conditions, your doctor may recommend additional testing.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: serum

Inform your healthcare provider if you are taking blood thinners. No special preparation required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

HbA1c

Frequently asked questions

HbA1c is a key indicator of diabetes management. Values above or below reference ranges can signal poor or improved control, helping doctors adjust treatments like medication or diet.
An HbA1c result is typically reported as a percentage (e.g., 6.5% or higher may indicate diabetes). Your doctor will interpret results in the context of your overall health and treatment plan.
How often should I get this test?
Typically, people with diabetes check HbA1c every 3–6 months, while others may get it less often. Your doctor will determine the best schedule for you.
Can lifestyle changes affect HbA1c results?
Yes! Regular physical activity, a balanced diet, and managing stress can help lower HbA1c levels over time. Consistent monitoring helps track these effects.
  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