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Hemoglobin A1c (HbA1c) with Mass Fraction Measurement

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 track 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
80657-0
Short code
Hg Q MFr Bld
Synonyms
Hg Q MFr Bld
Category
hematology
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

What HbA1c Tests Measure

HbA1c is a form of hemoglobin (the protein in red blood cells that carries oxygen) that gets attached to blood sugar (glucose) over time. This test quantifies the percentage of hemoglobin in your blood that is bound to glucose, providing a snapshot of your average blood sugar levels during the production of red blood cells (typically 2–3 months).

Why This Test Matters

Unlike daily blood sugar checks, HbA1c gives a broader picture of how well your diabetes is controlled. It’s especially useful for people with type 1 or type 2 diabetes, prediabetes, or those at risk for diabetes.

How the Test Works

Your blood sample is processed to measure the proportion of hemoglobin A1c relative to total hemoglobin. The test uses a specialized method to detect and quantify this fraction, often through techniques like high-performance liquid chromatography (HPLC) or immunoassay.

Sample Collection and Preparation

A small blood sample is drawn from your arm, typically in a vein. The blood is processed to separate hemoglobin components, and the HbA1c fraction is isolated and measured. This test is usually done on fresh or stored blood samples sent to a lab.

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 for diagnosing diabetes, monitoring treatment effectiveness, and assessing long-term blood sugar control. Levels above or below reference ranges can signal whether your diabetes is well-managed or if adjustments to treatment are needed.
HbA1c results are reported as a percentage. For example, a result of 6.5% or higher may indicate diabetes, while levels below 5.7% are often considered normal. Your doctor will interpret results in the context of your overall health and treatment plan.
What causes HbA1c levels to change?
Several factors can influence HbA1c levels, including diet, physical activity, medications (like insulin or oral diabetes drugs), stress, illness, or recent blood sugar fluctuations. If you’ve had significant changes in your lifestyle or health, discuss these with your provider.
How often should I get an HbA1c test?
The frequency depends on your health status. People with diabetes are often tested every 2–4 months, while those with prediabetes may need testing every 6–12 months. Your doctor will recommend a schedule 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