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Hemoglobin A1c (HbA1c) – Glycated Hemoglobin

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

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

Quick summary

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

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

Key facts at a glance

LOINC
13302-5
Short code
HLAC
Synonyms
—
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 This Test Matters

HbA1c is a key indicator of how well your body manages blood sugar over time. Unlike daily blood sugar checks, it provides a broader picture of your metabolic health, helping prevent complications like nerve damage or kidney disease.

How It’s Done

A small blood sample is taken from your arm, usually during a routine visit. The test measures the proportion of hemoglobin molecules bonded to glucose, expressed as a percentage.

What to Expect Before or After

No special preparation is needed, but inform your doctor if you’re taking blood thinners or have recent injuries. Results are typically ready within a few days.

Common Reasons for Testing

Doctors order HbA1c to diagnose diabetes, monitor treatment progress, or check for undiagnosed high blood sugar. It’s also useful for preconception planning or evaluating prediabetes.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HbA1c

Frequently asked questions

HbA1c is a gold standard for diabetes management because it correlates closely with long-term blood sugar levels. Values above 6.5% often signal diabetes, while lower values may indicate good control.
An HbA1c test can help detect prediabetes (5.7%–6.4%) or diabetes (6.5% or higher) before symptoms appear. It’s less affected by short-term fluctuations in blood sugar than daily measurements.
What does an abnormal HbA1c result mean?
A higher-than-normal HbA1c suggests poor blood sugar control, which may require lifestyle changes (like diet or exercise) or medication adjustments. A lower-than-normal result may indicate effective management, but always discuss results with your healthcare provider.
Can HbA1c be affected by other health conditions?
Yes, conditions like anemia, kidney disease, or certain medications (e.g., iron supplements) can influence HbA1c results. Your doctor may order additional tests if needed to interpret results accurately.
  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