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Glutamic Acid Decarboxylase Antibodies (Serum) – Autoimmune Serology Panel

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

This test measures antibodies against glutamic acid decarboxylase (GAD65), an enzyme linked to type 1 diabetes and other autoimmune conditions. It helps assess immune activity against pancreatic cells.

Quick summary

["This test may help diagnose or monitor autoimmune disorders affecting the pancreas or nervous system."]

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

Key facts at a glance

LOINC
58451-6
Short code
GAD65 Ab Ser-mCnc
Synonyms
GAD65 Ab Ser-mCnc
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 healthcare provider may recommend this test if you have symptoms like unexplained weight loss, frequent thirst, fatigue, or unexplained muscle weakness. It may also be used in patients with a family history of type 1 diabetes or other autoimmune diseases.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw a blood sample. If you’re on blood thinners, let your provider know before the test.

What the Test Measures

The test detects the presence of antibodies against GAD65, a protein involved in insulin production. Elevated levels suggest an autoimmune response targeting pancreatic cells.

Possible Results and Next Steps

If results are positive, further testing (like C-peptide levels) may be needed to confirm diabetes or other autoimmune conditions. Negative results do not rule out diabetes or other conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

GAD65 Antibodies

Frequently asked questions

What Does a Positive Result Mean?
A positive result suggests an autoimmune reaction against GAD65, which may indicate conditions like type 1 diabetes or autoimmune pancreatitis. Follow-up testing will determine next steps.
What If My Results Are Negative?
A negative result means no detectable antibodies against GAD65 in this sample, but it doesn’t rule out diabetes or other autoimmune diseases. Your provider may recommend retesting or additional tests.
How Often Should I Get Retested?
Retesting frequency depends on your symptoms and provider’s recommendations. If you have a known autoimmune condition, retesting may be part of ongoing monitoring.
  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