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Glutamic Acid Decarboxylase (GAD65) Antibodies, Serum

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

This test measures the presence of antibodies against a protein called glutamic acid decarboxylase (GAD65), which plays a role in insulin production in the pancreas. These antibodies are often linked to certain autoimmune conditions.

Quick summary

["This test helps diagnose or monitor autoimmune disorders affecting the pancreas."]

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

Key facts at a glance

LOINC
30347-9
Short code
GAD65 Ab Ser-sCnc
Synonyms
GAD65 Ab Ser-sCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Is This Test Done?

Your healthcare provider may order this test if you have symptoms of diabetes, such as unexplained weight loss, frequent urination, or extreme fatigue. It may also be used to check for autoimmune conditions like type 1 diabetes or other pancreatic-related autoimmune diseases.

What Does a Positive Result Mean?

A positive result means your body’s immune system is producing antibodies against GAD65. This can be an early sign of type 1 diabetes or other autoimmune conditions affecting the pancreas, though further testing is needed to confirm the diagnosis.

What Does a Negative Result Mean?

A negative result means no detectable antibodies against GAD65 were found in your sample. However, this does not rule out other autoimmune conditions or diabetes, so additional testing may still be required.

What to Expect During the Test

You will have a small amount of blood drawn from a vein in your arm. This is a quick and painless procedure, usually done in a clinic or lab setting. No special preparation is needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

GAD65 Antibodies

Frequently asked questions

What are GAD65 antibodies, and how do they relate to diabetes?
GAD65 antibodies are proteins your immune system mistakenly attacks in the pancreas. They are linked to type 1 diabetes, where the body’s immune system destroys insulin-producing cells. While a positive test can raise suspicion for diabetes, it is not definitive on its own.
How often should I get this test if I have symptoms of diabetes?
If you have symptoms like unexplained weight loss, frequent urination, or fatigue, your healthcare provider may recommend this test as part of a broader evaluation. They will determine the frequency based on your symptoms and medical history.
Can lifestyle changes affect the results of this test?
Lifestyle factors like diet or stress may influence overall health but are unlikely to directly affect antibody test results. However, they can impact symptoms related to autoimmune conditions, so maintaining a healthy lifestyle is still important.
  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