Skip to content

Hemoglobin A1c (HbA1c) – Glycated Hemoglobin

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

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

Quick summary

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

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

Key facts at a glance

LOINC
58453-2
Short code
Hgb Stl gastro lower IA-mCnc
Synonyms
Hgb Stl gastro lower IA-mCnc
Category
hematology
Sample
stool
Container
Clean container
Units
N/A
Ref low
10
Ref high
40
Critical range
7 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
84484
SNOMED
302774002
Specimen volume
5 g
Stability
Refrigerated: 24h, Frozen: 7d
TAT
4–24 hours
Order
routine

Why This Test Matters for Your Health

HbA1c is a key indicator of how well your body manages blood sugar over time. Unlike daily blood sugar checks, it provides a snapshot of trends that can help prevent complications like nerve damage, kidney disease, or heart problems.

How the Test Works

Blood is drawn from a vein, typically in your arm. The sample is processed to separate hemoglobin from other blood components, then analyzed to determine the proportion of glycated hemoglobin using immunoassay methods.

What to Expect Before the Test

No special preparation is needed, but fasting is not required. Wear comfortable clothing if you prefer, and let your healthcare provider know about any medications or conditions that might affect results.

Common Causes of Abnormal Results

Elevated HbA1c may suggest diabetes or poor blood sugar control, while lower levels could indicate recent blood sugar fluctuations or certain blood disorders. Always discuss results with your doctor.

Reference range

Adult: 10-40 U/LN/A

Specimen: stool

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HbA1c

Frequently asked questions

What does an abnormal HbA1c result mean?
An HbA1c result above the typical reference range may indicate diabetes or prediabetes. A result below the reference range could reflect recent changes in diet, exercise, or other factors. Your doctor will interpret results in the context of your overall health and symptoms.
Can HbA1c be affected by medications?
Yes, certain medications (e.g., iron supplements, blood thinners) or conditions (e.g., anemia, kidney disease) can influence HbA1c levels. Your doctor will consider these factors when reviewing your results.
How often should I get this test?
Typically, HbA1c is checked every 3–6 months for people with diabetes to monitor progress with treatment. Your doctor may adjust frequency based on your health needs and response to treatment.
  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