What Are GAD Antibodies?

Medically reviewed by Judith Marcin, MD on July 22, 2016Written by Ann Pietrangelo on July 22, 2016

GAD antibodies and diabetes

Your pancreas needs the enzyme glutamic acid decarboxylase (GAD) to function normally. Antibodies that target this enzyme are called GAD antibodies. An antibody is a protein that your immune system uses to attack foreign objects. Those foreign objects are often potentially harmful, such as viruses or bacteria.

Sometimes, the immune system makes antibodies that mistakenly attack normal, cells that aren’t harmful. When that happens, it’s called an autoimmune disorder.

About 70 percent of people with type 1 diabetes have GAD antibodies in their blood.

What is the purpose of a GAD antibodies test?

Once other diagnostic tools, such as glucose tolerance tests, indicate you have diabetes, the next step is to determine if it’s type 1 or 2. This is important because although they have a lot in common, these are two distinct conditions. Each requires a specific approach to management and treatment.

Your doctor may order a GAD test to learn more. You might also hear it called GADA or anti-GAD. Instead of a specific GAD test, you can also have an antibody panel to test for GAD and other antibodies as well. 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 of these tests are done with the use of a simple blood test. You won’t need to fast or do anything else to prepare. A healthcare professional will take blood from a vein in your arm and send it to a laboratory for analysis.

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

Learn more: Type 1 diabetes: Causes, symptoms, and more »

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 the pancreatic beta cells are destroyed, they can’t be repaired. Without insulin, glucose builds up in your blood, leaving your cells starved for energy.

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

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

  • cerebellar ataxia, which is a brain disorder that causes sudden, uncoordinated muscle movement
  • stiff person syndrome, which is a neurological condition that causes stiff muscles and muscle spasms
  • other autoimmune diseases, including rheumatoid arthritis and thyroid disease

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

Will the presence of GAD antibodies cause any symptoms?

You may not have any symptoms due to GAD antibodies in your blood. But if you’re being tested for GAD, chances are you’ve either had symptoms of diabetes or you’ve actually been diagnosed with diabetes after glucose tolerance testing.

The symptoms of diabetes include:

  • excessive thirst and hunger
  • frequent urination
  • irritability
  • blurry vision
  • fatigue
  • weakness
  • weight loss
  • cuts or sores that take a long time to heal

Can diabetes be treated?

Untreated, diabetes can lead to serious and even life-threatening complications, including:

  • vision problems
  • nerve damage
  • cardiovascular disease
  • kidney damage

Both type 1 and type 2 diabetes can be successfully managed.

If you have diabetes, the main goal is to keep your blood glucose levels under control. This will help prevent some of the potential complications of diabetes.

Diet is important in the management of diabetes. Keeping your glucose levels within an optimal range throughout the day takes vigilance. Your doctor will give you recommendations for a diet that’s high in nutritional value, but low in empty calories.

Read more: Type 1 diabetes diet »

Engaging in regular physical activity is another way to keep your blood glucose levels in the optimal range.

If you have type 2 diabetes, you may or not need medication. If you do, several oral medications are available to help keep glucose levels under control.

You cannot survive without insulin. Everyone with type 1 diabetes and some people with type 2 diabetes need insulin therapy.

Insulin therapy requires monitoring your blood glucose levels, so you know when and how much insulin you need. Insulin is taken by an injection just under the skin. You should rotate injection sites to avoid skin irritation.

Some types of insulin are meant to act quickly and last for a short time. Others are designed to be long acting. Your doctor will advise you how and when to use each type.

You can also use an insulin pump, which is a device you can wear on the outside of your body. The pump makes it easier to deliver insulin when you need it. This is especially helpful if you have type 1 diabetes or you have type 2 and you need insulin injections several times per day.

Your treatment plan may change over time. If you have any complications of diabetes, your doctor will also need to address those.

What is the outlook?

There’s no cure for type 1 diabetes and it isn’t reversible. Even when your glucose levels stay in your optimal zone for a long time, it still requires a lifelong commitment to disease management and insulin therapy.

If you have type 2 diabetes, it’s possible to get your blood glucose levels in the normal range for long periods and reduce or eliminate your need for medication. You’ll always need to stick to healthy lifestyle habits and keep an eye on your blood glucose levels to be certain you’re still producing the right amount of insulin.

Treatment for diabetes has come a long way. The medications available today help keep diabetes under control and reduce the risk of complications.

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