antibodies to GAD65

Blood test (GAD) measures if you make antibodies against glutamate decarboxylase. (serum)

GAD65-Ak is also known as Glutamate Decarboxylase-Ak, Glutamic Acid Decarboxylase-Ak and measures autoantibodies for autoimmune diagnostics in diabetes mellitus.

In the jungle of terms and jargon surrounding type 1 diabetes you will sometimes come across the word GAD65. Especially around the diagnosis. What is GAD65 and what else might it be useful for in type 1 diabetes?

GAD65 (glutamic acid decarboxylase, 65 says something about its size) is a special protein. It is an enzyme that makes an important brain signaling substance, GABA. The protein GAD65 also makes GABA in the insulin-making beta cells in the pancreas. Again, it acts as a signaling agent, but between the cells of the islets of Langerhans.

The immune system may see GAD65 as a foreign invader, even though it is a very useful protein. Then the body starts making antibodies against GAD. Those antibodies (autoantibodies) can be seen as the 'smoke' to the 'fire' of the immune response against the beta cells. That 'smoke' can exist long before the diagnosis of type 1 diabetes; you can even see type 1 diabetes coming with it.

Also other substances for diagnosisDoctors
look at these antibodies in the blood to make a confident diagnosis of autoimmune diabetes type 1. They often test GAD65 together with two other antibodies, IA2 and ZnT8. This gives more certainty because sometimes not all of the antibodies are present at the same time.

reference values: <1.0 U/ml method
: radioimmunoassay (RIA)

This test can be done in case of suspicion of;

• Diabetes mellitus type 1 and
• LADA (late onset autoimmune diabetes in adults);
• Risk assessment in first-degree relatives with diabetes mellitus type 1
• The stiff-man syndrome (Moersch-Woltmann syndrome, a very rare disorder of the nervous system. It is a disorder of the transition from nerve to muscle, which is characterized by increasing contraction of muscles. This causes severe spasms.

The prevalence of GAD65-al. in type I diabetes mellitus is between 65 and 80% when it first occurs. The antibodies may also be detectable months to years before the disease manifests. According to the current state of knowledge, the detection of only one diabetic antibody is associated with a low diabetes risk (<15%). Only the detection of multiple antibodies is an indication of the presence or development of autoimmune diabetes.

The clinical sensitivity of GAD65 antibodies to stiff-person syndrome is high - there are usually very high antibody concentrations.

The test is accredited

It is recommended that you also measure whether you produce antibodies to insulin. (serum)