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Serum or Plasma Hemoglobin A1c (HbA1c) Concentration

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

This test measures the average level of hemoglobin A1c in your blood over the past 2–3 months, reflecting your long-term blood sugar control.

Quick summary

["HbA1c helps doctors assess how well your diabetes is managed over time."]

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

Key facts at a glance

LOINC
99921-9
Short code
S haematobium UrnS Ql Comp Assist
Synonyms
S haematobium UrnS Ql Comp Assist
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
computer-assisted
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What HbA1c Tests Measure

HbA1c is a form of hemoglobin (the protein in red blood cells that carries oxygen) that has attached a sugar molecule (glucose). This attachment reflects your average blood sugar levels during the production of red blood cells, which live for about 3 months. The test is done on serum or plasma, the liquid part of blood after clotting or separation.

How HbA1c Works in Diabetes Management

Unlike blood sugar tests that only show your current glucose level, HbA1c provides a snapshot of your blood sugar trends over time. It’s a key tool for diagnosing diabetes, monitoring treatment effectiveness, and preventing complications like nerve damage or kidney disease.

Why HbA1c Matters for You

Regular HbA1c testing helps doctors adjust medications, lifestyle advice, or other treatments to keep your blood sugar within a healthy range. It’s especially important if you have diabetes, prediabetes, or are at risk for developing these conditions.

What to Expect During the Test

You’ll have a small needle inserted into your arm or finger to draw a blood sample. The test is quick and painless. The lab will separate the serum or plasma from your blood cells and analyze the hemoglobin fraction containing A1c.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance of HbA1c Results

Short name

HbA1c

Frequently asked questions

What does an abnormal HbA1c result mean?
An HbA1c result above the typical range (often 4–6% for healthy individuals, higher in diabetes) may indicate poor blood sugar control. Repeatedly high levels can increase the risk of diabetes-related complications. A result below the typical range might suggest your blood sugar is consistently lower than usual, which could require monitoring or adjustments to your treatment plan.
How often should I get an HbA1c test?
If you have diabetes, your doctor may recommend HbA1c testing every 3–6 months to track your progress. If you’re prediabetic or at risk, testing every 1–2 years may be advised. Follow your healthcare provider’s guidance based on your specific health needs.
Can lifestyle changes affect HbA1c results?
Yes! Diet, exercise, weight management, and medications can all impact your HbA1c levels. Small, sustainable lifestyle changes—like eating balanced meals, staying active, and avoiding sugary snacks—can help improve your blood sugar control 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 16, 2026. · Read our editorial policy