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Hemoglobin A1c (HbA1c) with Glycated Hemoglobin Analysis

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 long-term diabetes control and adjust treatment plans."]

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

Key facts at a glance

LOINC
4564-1
Short code
Hgb C-Harlem Bld Ql
Synonyms
Hgb C-Harlem Bld Ql
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 HbA1c Tests Measure

HbA1c tests specifically quantify the proportion of hemoglobin molecules bonded to glucose, indicating how consistently your blood sugar has been within or outside healthy ranges. This is distinct from immediate blood sugar readings (like fasting glucose) and provides a broader picture over time.

Why This Test Matters for You

Unlike daily blood sugar checks, HbA1c offers a snapshot of your glucose management over months. It’s particularly useful for diagnosing diabetes, assessing treatment effectiveness, or identifying trends in blood sugar control.

How the Test Works

Blood is drawn, and the hemoglobin is separated from other blood components. The test then measures the percentage of hemoglobin molecules that have sugar attached, typically using an immunoassay or related method to detect glycated hemoglobin.

Common Uses in Healthcare

Doctors use HbA1c to diagnose type 1 or type 2 diabetes, monitor pre-diabetes, or evaluate how well diabetes medications or lifestyle changes are working. It’s also used in pregnancy to check for gestational diabetes.

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

What Does an HbA1c Test Tell Me About My Blood Sugar?
An HbA1c test shows your average blood sugar levels over the past 2–3 months. For example, an HbA1c of 7% means your blood sugar was likely around 154 mg/dL (8.6 mmol/L) on average during that time. It’s not a single snapshot but a trend indicator.
How Often Should I Get an HbA1c Test?
If you have diabetes, your doctor may recommend testing every 3–6 months to monitor progress. For pre-diabetes or those at high risk, testing once a year is often sufficient. Frequency can vary based on your health status, treatment plan, and other factors.
Can HbA1c Test Results Change Over Time?
Yes, HbA1c levels can fluctuate based on diet, activity, illness, stress, or medications. For example, infections or illness may temporarily raise HbA1c, while improved diabetes management (like better diet or exercise) can lower it. Your doctor will interpret results in the context of your overall health.
  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