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Hemoglobin A1c (HbA1c) with Mass Fraction Measurement

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

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

Quick summary

["Helps doctors assess long-term blood sugar control for diabetes management."]

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

Key facts at a glance

LOINC
35126-2
Short code
Hgb O-Arab MFr Bld
Synonyms
Hgb O-Arab MFr Bld
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
12
Ref high
17.5
Critical range
7 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85018
SNOMED
900000000000003004
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 molecules attached. This reflects your average blood glucose levels over time, typically 2–3 months, because red blood cells live about that long. It’s a key indicator of how well your diabetes is controlled.

Why Is This Test Important?

HbA1c is crucial for diagnosing diabetes (if levels are high) and monitoring treatment effectiveness. It provides a more stable picture than daily blood sugar checks alone.

How Is This Test Performed?

A small blood sample is taken from your arm, usually via a vein. The sample is analyzed to determine the percentage of glycated hemoglobin using a specialized laboratory method.

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: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A

Specimen: whole-blood

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

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 recommended every 3–6 months for people with diabetes, depending on your treatment plan and blood sugar goals.
Can diet or exercise affect HbA1c results?
Yes, lifestyle changes like diet and exercise can lower HbA1c levels over time. However, results take weeks to reflect these changes.
What if my HbA1c is higher than expected?
A higher HbA1c may signal poor blood sugar control. Your doctor may adjust medications, recommend dietary changes, or check for other health conditions affecting glucose metabolism.
  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