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Hemoglobin A1c (Glycated Hemoglobin) with Mass Fraction Measurement

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

["HbA1c helps doctors track diabetes or prediabetes and adjust treatment plans."]

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

Key facts at a glance

LOINC
96595-4
Short code
HbA1c MFr DBS
Synonyms
HbA1c MFr DBS
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
4
Ref high
5.6
Critical range
2 N/A – 14 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
83037
SNOMED
43387009
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

Why Is This Test Done?

Your healthcare provider may order this test to monitor long-term blood sugar control, especially if you have diabetes, prediabetes, or are at risk for developing these conditions. It’s also used to assess how well your current treatment is working.

How Is the Test Performed?

A small blood sample is taken from your arm, usually during a routine visit to your doctor’s office or a lab. The test measures the proportion of glycated hemoglobin in your red blood cells using a specialized method.

What Do the Results Mean?

Results are expressed as a percentage, but exact values depend on your lab and healthcare team. Higher percentages generally indicate poorer blood sugar control, while lower percentages suggest better management.

Common Causes of Abnormal Results

Elevated HbA1c levels may be due to uncontrolled diabetes, poor diet, or certain medications. Lower-than-expected levels might indicate underdiagnosed diabetes or rare conditions affecting red blood cell lifespan.

Reference range

Normal: 4.0-5.6%N/A

Specimen: serum

Fasting for 8-12 hours required. Water is permitted. Avoid chewing gum and smoking before the test.

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 measure exactly?
It measures the percentage of your hemoglobin molecules that have sugar (glucose) attached to them, reflecting your average blood sugar levels over the past 2–3 months.
Can HbA1c results change if I’ve recently had a blood donation?
Yes, recent blood donation may temporarily affect results because it can alter red blood cell composition. Your provider may ask to wait a few weeks before retesting if this occurred.
Is HbA1c the same as fasting blood sugar?
No. HbA1c is a long-term measure of blood sugar control, while fasting blood sugar tests check your blood sugar level after an overnight fast, giving a snapshot of recent glucose levels.
  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