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Glutamic Acid Decarboxylase Antibody (Anti-GAD65) in Serum

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

This test measures antibodies against glutamic acid decarboxylase (GAD65), a protein linked to type 1 diabetes and certain autoimmune neurological conditions. It helps assess immune activity in the pancreas or nervous system.

Quick summary

["This test may help diagnose or monitor conditions where the immune system attacks the body’s own tissues."]

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

Key facts at a glance

LOINC
111335-6
Short code
GAD65 Ab Msmt Ser
Synonyms
GAD65 Ab Msmt Ser
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 This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms like unexplained weight loss, frequent thirst, fatigue, or signs of nerve damage. It could also be used in people with a family history of type 1 diabetes or autoimmune disorders.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample from a vein, usually in a doctor’s office or lab. The test is quick and typically painless.

What the Results Mean

High levels of anti-GAD65 antibodies suggest an autoimmune response targeting GAD65, which may indicate conditions like type 1 diabetes or other autoimmune diseases affecting the pancreas or nerves.

Common Conditions Linked to Positive Results

Positive results are most strongly associated with type 1 diabetes, but they may also appear in other autoimmune conditions like stiff-person syndrome or certain neurological disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: This test is critical for diagnosing or confirming suspected autoimmune conditions affecting the pancreas or nervous system. It helps guide treatment decisions, such as managing diabetes or addressing nerve-related symptoms.

Short name

Anti-GAD65 Antibody

Frequently asked questions

What does a positive result mean for my health?
A positive result suggests your immune system may be attacking GAD65, which is linked to autoimmune diseases. Your doctor will discuss next steps, such as further testing or treatment plans tailored to your symptoms and medical history.
Can lifestyle changes affect this test result?
While diet and exercise can influence overall health, they may not directly affect antibody levels in this test. Your doctor will consider your overall health and symptoms when interpreting results.
How often will I need this test?
Your doctor will determine how often you need this test based on your symptoms, medical history, and treatment needs. Follow-up may be scheduled as part of ongoing monitoring for your condition.
  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