Skip to content

Hemoglobin A1c (Glycated Hemoglobin) by High-Performance Liquid Chromatography (HPLC)

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

This test measures the average blood sugar levels over the past 2–3 months by detecting how much of your hemoglobin is coated with sugar.

Quick summary

["Helps track long-term diabetes control and glucose management."]

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

Key facts at a glance

LOINC
25400-3
Short code
E histolyt Ab Titr Ser IF
Synonyms
E histolyt Ab Titr Ser IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 blood sugar has been managed over time. Unlike daily blood sugar checks, it provides a broader picture of your average glucose levels, helping doctors assess diabetes treatment effectiveness and adjust care plans accordingly.

How It Works

Your blood sample is analyzed using high-performance liquid chromatography (HPLC), a precise method that separates and measures the proportion of hemoglobin bound to glucose. This reflects your average blood sugar levels over months.

What to Expect Before the Test

No special preparation is needed. A small blood sample is taken from your arm, similar to a routine blood draw. If you’re pregnant, have kidney disease, or take certain medications, your doctor may advise timing it around your usual meals or insulin doses.

Common Causes for Testing

Doctors order HbA1c tests to diagnose diabetes, monitor pre-diabetes, or evaluate diabetes management in people with type 1, type 2, or gestational diabetes. It’s also used to check for complications like nerve damage or kidney issues linked to chronic high blood sugar.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

HbA1c

Frequently asked questions

What does an abnormal HbA1c result mean?
An HbA1c result above the typical range (often 4–6% for healthy individuals, higher in diabetes) suggests poor blood sugar control. Repeatedly high levels may indicate uncontrolled diabetes, while persistently low levels could raise concerns about hypoglycemia or over-treatment.
How often should I get this test?
If you have diabetes, your doctor may recommend testing every 2–3 months to track progress. For pre-diabetes or those at high risk, testing once a year may suffice, but adjustments depend on your health goals and treatment plan.
Can lifestyle changes affect HbA1c results?
Yes! Improving diet, increasing physical activity, or managing stress can lower HbA1c levels over time. Conversely, poor diet, lack of exercise, or illness may temporarily raise it. Results can shift gradually, so consistency in lifestyle matters.
  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