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Hemoglobin A1c (Glycated Hemoglobin) – Quantitative Measurement

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

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

Quick summary

["HbA1c helps doctors track diabetes management and long-term blood sugar control."]

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

Key facts at a glance

LOINC
40718-9
Short code
Heinz Bod/RBC NFr Bld
Synonyms
Heinz Bod/RBC NFr Bld
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85041
SNOMED
900000000000003001
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 Does This Test Measure?

HbA1c measures the proportion of hemoglobin molecules that have sugar (glucose) bound to them. This binding occurs over time as blood sugar levels fluctuate, so it provides a snapshot of your average blood sugar over several weeks.

Why Is This Test Important?

Unlike daily blood sugar checks, HbA1c gives a broader picture of how well your diabetes or prediabetes is controlled, helping prevent complications like nerve damage or kidney disease.

How Is This Test Performed?

A small blood sample is taken from your arm, typically via a fingerstick. The test is usually done in a lab using an automated analyzer to measure the glycated hemoglobin levels.

What Are Common Results?

Results are reported as a percentage (e.g., 6.5%). While exact ranges vary by lab, higher percentages generally indicate poorer blood sugar control.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

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 tell me about my health?
It shows your average blood sugar levels over the past 2–3 months, helping doctors determine if your diabetes is well-managed or if adjustments to treatment are needed.
How often should I get this test?
Typically, people with diabetes get tested every 3–6 months, while those with prediabetes may need testing every 1–2 years unless advised otherwise.
Can lifestyle changes affect my HbA1c results?
Yes, diet, exercise, and managing stress can improve HbA1c levels. Small, consistent changes often lead to measurable improvements over time.
  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