What is Glutamic Acid Decarboxylase(GAD) Antibody?

Your doctor will use diagnostic tools to diagnose diabetes, such as checking for high glucose and a high HbA1c. Once they can diagnose diabetes, they’ll take steps to determine if it’s type 1 or 2.

Type 1 diabetes and type 2 diabetes are two distinct conditions. Each requires a specific approach to management and treatment.
Your doctor may order a GAD test to find out more about your condition. You might also hear this test referred to as GADA or anti-GAD. Or your doctor may recommend an autoantibody panel to test for GAD and other antibodies.

Other antibodies associated with type 1 diabetes include:

• islet cell cytoplasmic autoantibodies (ICAs)
• insulinoma-associated-2 autoantibodies (IA-2As)
• insulin autoantibodies (IAAs), which are more common in children than adults

All these tests are done through a simple blood test. You won’t need to do anything to prepare, such as fasting. A healthcare provider will take blood from a vein in your arm and send it to a laboratory for analysis.

If GAD or any of the other autoantibodies are found, it means you most likely have type 1 diabetes. If no GAD or other autoantibodies are found, you probably have type 2.

What causes high GAD antibody levels?

Type 1 diabetes is the result of an immune system malfunction. It starts when your immune system attacks and destroys beta cells in your pancreas. These are the cells that produce insulin, a hormone necessary to regulate blood glucose levels.

Once your immune system destroys pancreatic beta cells, they can’t be repaired. Without insulin, glucose builds up in your blood and leaves your cells starved for energy.

In type 2 diabetes, your pancreas may not be producing enough insulin or your body isn’t using it efficiently. Type 2 diabetes starts as insulin resistance. The presence of GAD autoantibodies indicates an immune system attack, which points to type 1 diabetes.

Type 1 diabetes isn’t the only reason someone might have GAD autoantibodies. These antibodies are also linked to other conditions, which include:

• Cerebellar ataxia. This brain disorder causes sudden uncoordinated muscle movement.
• Stiff person syndrome. This neurological condition causes stiff muscles and muscle spasms.
• Other autoimmune diseases. These include rheumatoid arthritis (RA) and thyroid disease.

If you’ve been diagnosed with diabetes and you have GAD autoantibodies, it’s likely that you have type 1 diabetes.