GAD65 (GLUTAMIC ACID DECARBOXYLASE) IGG TEST
(Flat ₹1401 OFF - Sanovra Lab)
Report Time: 2nd Working Day | Sample: Blood (Serum) | Test Code: ES066
Anti-GAD65 Antibodies are specific autoantibodies produced by the immune system that attack the enzyme Glutamic Acid Decarboxylase (GAD). This enzyme is crucial for the function of the pancreas and the nervous system. The presence of these antibodies is a hallmark of autoimmune diseases.
This test is the Gold Standard for differentiating between Type 1 and Type 2 Diabetes (especially in adults, known as LADA). It is also the primary diagnostic tool for rare but severe neurological disorders like Stiff Person Syndrome (SPS) and Cerebellar Ataxia.
What is GAD65? The Biological Role
To understand the test, you must understand the enzyme. GAD (Glutamic Acid Decarboxylase) is an enzyme required to produce GABA (Gamma-Aminobutyric Acid), a neurotransmitter that calms nerve activity.
GAD is found in two main places:
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✔The Pancreas: Specifically in the beta-cells that make insulin.
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✔The Nervous System: In the brain and spinal cord, where it helps regulate muscle movement.
When the immune system makes a mistake and produces IgG antibodies against GAD65, it attacks these two areas, leading to either Diabetes or Neurological disorders.
Why is this Test Performed? (Clinical Uses)
This is a specialized test ordered by Endocrinologists and Neurologists for specific, complex conditions:
1. Type 1 Diabetes vs. Type 2 Diabetes
Sometimes, it is hard to tell if an adult has Type 2 Diabetes (lifestyle-related) or LADA (Latent Autoimmune Diabetes in Adults). LADA is actually a slow-moving form of Type 1 Diabetes.
[Image of pancreas insulin beta cells]-
➤Positive GAD65: Confirms autoimmune destruction of the pancreas (Type 1 or LADA). Oral pills usually won't work long-term; these patients will eventually need insulin.
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➤Negative GAD65: Suggests Type 2 Diabetes, which can often be managed with diet and tablets.
2. Stiff Person Syndrome (SPS)
This is a rare neurological disorder (famously affecting singer Celine Dion) characterized by fluctuating muscle rigidity and painful spasms. Extremely High Levels of GAD65 antibodies are the definitive marker for this condition. The antibodies stop the production of GABA, causing nerves to over-fire and muscles to lock up.
3. Cerebellar Ataxia
Some patients experience unexplained clumsiness, loss of balance, or slurred speech. If MRI scans are normal, doctors test for GAD65 antibodies to see if the immune system is attacking the cerebellum (the balance center of the brain).
Interpreting Your Results
The interpretation depends heavily on how high the levels are. Unlike a pregnancy test (Yes/No), the quantity matters.
| Level | Clinical Significance |
|---|---|
| Negative (< 5 IU/mL) | Normal. No autoimmune reaction detected against GAD. |
| Low Positive | Often seen in Type 1 Diabetes or LADA. It confirms the pancreas is under autoimmune attack. |
| Extremely High (> 2000 IU/mL) | Strongly indicative of Neurological Disorders like Stiff Person Syndrome (SPS) or Autoimmune Encephalitis. |
Preparation & Procedure
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✔Fasting: No fasting is required. You can eat and drink normally.
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✔Sample: A standard blood draw (Serum).
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✔Processing Time: This is a complex ELISA/RIA test. The report is generated by the 2nd Working Day.
Frequently Asked Questions (FAQs)
Yes. Antibodies can appear in the blood years before symptoms of Diabetes start. This is often seen in relatives of Type 1 Diabetics who are screened for risk.
Currently, there is no cure, but treatments (like IVIG and muscle relaxants) can manage symptoms. High GAD65 levels help doctors diagnose it early to start treatment sooner.
LADA patients are often thin and active (unlike typical Type 2 patients). They are frequently misdiagnosed as Type 2 but do not respond well to standard diabetes drugs. A GAD65 test is the best way to correct this diagnosis.
For Diabetes diagnosis, usually one positive test is enough. For Stiff Person Syndrome, doctors may monitor levels over time to see if treatment (like plasmapheresis) is lowering the antibody count.
Get a Definitive Diagnosis
Whether clarifying a Diabetes diagnosis or investigating neurological symptoms, the GAD65 test provides the answers you need.
Disclaimer: The information provided here is for educational purposes only and does not constitute medical advice. Laboratory results should always be interpreted by a qualified Endocrinologist or Neurologist in the context of clinical findings.