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Hemoglobin A1c (HbA1c) 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 assess long-term blood sugar control, especially important for managing diabetes."]

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

Key facts at a glance

LOINC
77475-2
Short code
Deprecated Hind+Mid ft-L XR Harris
Synonyms
Deprecated Hind+Mid ft-L XR Harris
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
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

What HbA1c Measures

HbA1c reflects the amount of glucose (sugar) that has attached to hemoglobin, the protein in red blood cells that carries oxygen. It’s a snapshot of your blood sugar levels over time, accounting for daily fluctuations that a single blood sugar test might miss.

How It’s Used in Diabetes Care

Doctors use HbA1c to diagnose diabetes (typically ≥6.5%), monitor treatment progress, and adjust medications like insulin or oral diabetes drugs to keep blood sugar within target ranges.

Sample Collection and Preparation

A small blood sample is drawn from your arm, usually during a routine visit. The blood is processed to separate red blood cells from plasma, then analyzed by HPLC to measure the percentage of hemoglobin bound to sugar.

When You Might Need This Test

HbA1c is ordered at diagnosis of diabetes, every 3–6 months for stable diabetes management, or if you have prediabetes (blood sugar levels between normal and diabetic). It’s also used to check for complications like nerve damage or kidney disease linked to long-term high blood sugar.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

HbA1c is a gold-standard test for diabetes management because it provides a reliable, long-term measure of glycemic control. Lower HbA1c levels (typically <7%) correlate with fewer diabetes complications, while higher levels may indicate poor control and require medical intervention.

Short name

HbA1c

Frequently asked questions

Why might my HbA1c be different from what I remember from my last test?
Several factors can influence HbA1c results, including recent blood loss (e.g., from surgery or menopause), anemia, or certain medications. If you’ve had recent blood transfusions or iron supplements, your HbA1c may be artificially lower. Always discuss any changes with your healthcare provider.
How often should I get an HbA1c test if I have diabetes?
For most people with diabetes, HbA1c testing is recommended every 3–6 months. Your doctor may adjust this frequency based on your blood sugar goals, stability, and overall health. Regular testing helps catch issues early and ensures your treatment plan stays effective.
Can HbA1c be affected by diet or exercise?
While diet and exercise influence your daily blood sugar levels, they don’t directly change HbA1c. However, maintaining healthy habits can help keep your HbA1c within a target range over time. If you notice sudden changes in your HbA1c, talk to your doctor to rule out other factors.
  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