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Hemoglobin A1c (HbA1c) – Glycated Hemoglobin

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

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

Quick summary

["HbA1c helps track long-term blood sugar control, useful for diabetes management."]

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

Key facts at a glance

LOINC
73949-0
Short code
JWH-018 Bld Ql
Synonyms
JWH-018 Bld Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

Why This Test Matters for You

HbA1c is a key indicator of how well your blood sugar has been managed over time. Unlike daily blood sugar checks, it provides a broader picture of your glucose control, helping doctors assess whether your diabetes treatment is effective.

How It Works

Your blood sample is tested to determine the proportion of hemoglobin molecules that have sugar molecules attached. This test uses a specialized method to measure this glycated hemoglobin percentage.

What to Expect Before the Test

No special preparation is needed. You may have a fingerstick blood draw, similar to a regular blood test. If you’re using insulin or other diabetes medications, check with your provider if you should fast or adjust timing.

Common Causes of Results Outside Normal Range

High HbA1c levels may suggest poor blood sugar control, often linked to diabetes or prediabetes. Low levels are less common but could indicate very low blood sugar or certain medical conditions.

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 this test?
Typically, people with diabetes check their HbA1c every 2–3 months, while others may get it less frequently based on their health status and doctor’s recommendations.
What does an abnormal result mean?
An abnormal result means your average blood sugar levels may be too high or too low. Your doctor will discuss next steps, such as adjusting medications, improving diet, or increasing physical activity.
Can diet or exercise affect HbA1c results?
Yes, lifestyle changes like eating balanced meals, exercising regularly, and managing stress can improve HbA1c levels over time. Your doctor may recommend specific strategies tailored to your needs.
  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