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Hemoglobin A1c (HbA1c) measured by high-performance liquid chromatography (HPLC)

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

This test measures the percentage of hemoglobin that is coated with sugar, reflecting your average blood sugar levels over the past 2–3 months.

Quick summary

["HbA1c helps doctors track long-term diabetes control and assess risk for complications."]

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

Key facts at a glance

LOINC
90927-5
Short code
RET gene rearrange Bld/T FISH
Synonyms
RET gene rearrange Bld/T FISH
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
fish
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 reflects how your blood sugar levels have been managed over time. It’s a stable form of hemoglobin that picks up sugar molecules during red blood cell production, so it’s a reliable indicator of average glucose exposure in recent months.

How the Test Works

Your blood sample is analyzed using HPLC, which separates hemoglobin variants based on their sugar content. The test detects the proportion of hemoglobin bound to glucose (HbA1c) compared to total hemoglobin.

Why It Matters for You

HbA1c is critical for diagnosing diabetes (if levels are consistently high) and monitoring treatment effectiveness. It’s less affected by short-term fluctuations in blood sugar than daily glucose checks.

Common Reasons for Testing

Doctors order HbA1c to diagnose type 1 or type 2 diabetes, evaluate prediabetes risk, or assess how well diabetes medications are working. It’s also used in pregnancy to monitor gestational diabetes.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HbA1c

Frequently asked questions

How often should I get an HbA1c test?
Typically, adults with diabetes get tested every 2–4 months to adjust treatment. If you have prediabetes, your doctor may recommend testing every 6–12 months. Children or adolescents with diabetes may need more frequent checks.
What do my results mean?
Results below 5.7% suggest normal glucose levels. Between 5.7% and 6.4% indicates prediabetes, while 6.5% or higher may signal diabetes. Your doctor will interpret results in the context of your overall health and treatment plan.
Can lifestyle changes affect HbA1c results?
Yes! Improving diet, exercise, or managing stress can lower HbA1c levels over time. Even small changes, like reducing sugar intake or increasing physical activity, may show improvements in follow-up tests.
  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