Skip to content

Hemoglobin A1c (HbA1c) with Immunoassay Method

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

This test measures the average blood sugar (glucose) levels over the past 2–3 months by analyzing your red blood cells.

Quick summary

["Helps doctors track long-term diabetes control and adjust treatment plans."]

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

Key facts at a glance

LOINC
89448-5
Short code
OB Hosp Letter
Synonyms
OB Hosp Letter
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
obstetrics
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 This Test Measures

HbA1c reflects your blood sugar levels over time by binding to hemoglobin in your red blood cells. It’s a key indicator of how well your diabetes is managed, especially in people with type 1 or type 2 diabetes.

Why It’s Done

Doctors order HbA1c tests to assess long-term blood sugar control, monitor diabetes progression, or evaluate treatment effectiveness. It’s often used alongside daily blood glucose checks.

How It’s Performed

A small blood sample is taken from your arm, usually via a fingerstick. The sample is sent to a lab where an immunoassay detects hemoglobin bound to glucose.

What to Expect Before the Test

No special preparation is needed, but inform your doctor if you’re taking diabetes medications or supplements that may affect blood sugar.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

HbA1c levels above 7% may indicate poor diabetes management, while levels below 6.5% suggest good control. Values between 6.5% and 7% may require closer monitoring or adjustments to treatment.

Short name

HbA1c

Frequently asked questions

How often should I get an HbA1c test?
Typically, people with diabetes get tested every 2–4 months, while others may need it less frequently based on their health status and treatment plan.
Can diet or exercise affect my HbA1c results?
Yes, lifestyle changes like diet and exercise can influence HbA1c levels. However, the test measures long-term trends, so short-term fluctuations won’t drastically alter the result.
What do abnormal HbA1c results mean?
High levels may signal uncontrolled diabetes, while low levels could indicate over-treatment or other health conditions. Always discuss results with your healthcare provider for personalized guidance.
  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