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Glutamic Acid Decarboxylase (GAD65) Antibody, Serum

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

This test measures antibodies to a protein called glutamic acid decarboxylase (GAD65), which plays a role in insulin production. It may help diagnose or monitor certain autoimmune conditions affecting the pancreas or nervous system.

Quick summary

["This test helps identify potential autoimmune disorders linked to GAD65 antibodies."]

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

Key facts at a glance

LOINC
94699-6
Short code
GAD65 Ab Ser IA-sCnc
Synonyms
GAD65 Ab Ser IA-sCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 healthcare provider may order this test if you have symptoms like unexplained diabetes, nerve-related issues (e.g., neuropathy), or other autoimmune symptoms. It may also be used to assess conditions like type 1 diabetes, diabetes-related nerve damage, or other autoimmune disorders affecting the pancreas or brain.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, typically drawn from your arm. If you’re on blood-thinning medication, let your provider know before the test.

What the Results Mean

High levels of GAD65 antibodies may suggest an autoimmune reaction targeting GAD65, potentially linked to conditions like diabetes or nerve disorders. Results are interpreted by your healthcare provider in the context of your symptoms and medical history.

Common Conditions Linked to This Test

Positive results may be associated with type 1 diabetes, diabetes-related nerve damage (diabetic neuropathy), or other autoimmune conditions affecting the pancreas or nervous system. Your provider will discuss findings with you.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

GAD65 Antibody (Serum)

Frequently asked questions

What does a positive result mean for my health?
A positive result suggests your immune system may be producing antibodies against GAD65, which could be linked to autoimmune conditions like type 1 diabetes or nerve-related issues. Your provider will review the results with you to determine next steps, which may include further testing or monitoring.
Will this test affect my diabetes management?
This test is not a direct measure of blood sugar control. If you have diabetes, your provider will use this test alongside other factors (like glucose levels, symptoms, and treatment response) to guide care. Follow your usual diabetes management plan unless advised otherwise.
Can I fast before this test?
No fasting is required for this blood test. However, if you’re on blood-thinning medications, let your healthcare provider know before the test to avoid complications.
  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