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Hemoglobin A1c (HbA1c) with 24-hour fluid collection

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

This test measures the average blood sugar level over the past 2–3 months by analyzing hemoglobin in your red blood cells.

Quick summary

["Helps track long-term blood sugar control for diabetes management."]

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

Key facts at a glance

LOINC
50598-2
Short code
HPA-15 Bld
Synonyms
HPA-15 Bld
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 This Test Measures

HbA1c reflects the percentage of hemoglobin molecules attached to glucose, providing a snapshot of your blood sugar trends over time. It accounts for variations in red blood cell lifespan and is less affected by short-term fluctuations in blood sugar levels.

Why It’s Used

Doctors use HbA1c to diagnose diabetes, monitor treatment effectiveness, and assess long-term blood sugar control. A 24-hour fluid collection may be used to standardize sample preparation for consistency.

How It’s Performed

A small blood sample is taken from your arm. The test measures the proportion of hemoglobin bound to glucose using immunoassay methods, such as electrochemiluminescence or chemiluminescent immunoassay.

What to Expect Before the Test

No special preparation is needed, but inform your provider if you’re taking certain medications (e.g., blood thinners) or have recent blood transfusions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HbA1c (24h)

Frequently asked questions

HbA1c is critical for diagnosing diabetes (typically ≥6.5%) and assessing glycemic control. Lower values suggest better blood sugar management, while higher values indicate poor control and may warrant adjustments to treatment.
An HbA1c test helps detect diabetes early and guides treatment plans, such as diet, exercise, or medication. It’s often checked annually or more frequently if you have unstable blood sugar.
This test doesn’t show immediate blood sugar spikes or drops, so it’s best used alongside other metrics like fasting glucose or continuous glucose monitors.
A 24-hour fluid collection ensures consistency in sample preparation, reducing variability in results. If your provider orders this, follow their instructions for timing and handling the sample.
Is fasting required? No, unlike some blood sugar tests, HbA1c doesn’t require fasting.
How long does it take to get results? Results are typically available within 1–3 business days, depending on lab processing times.
  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