Autoimmune diagnostics - diabetes mellitus

Antibodies to GAD 65, IA 2 and Insulin

Reliable indicators for the early detection of type 1 diabetes and differential diagnosis between type 1 and type 2 diabetes.

Type 1 diabetes mellitus is a chronic autoimmune disease. It is caused by the selective destruction of insulin-producing pancreatic ß-cells, whereby autoantibodies are formed against substances and structures inside the ß-cells. These antibodies are important markers for identifying people with an increased risk of developing diabetes at an early age and for making it possible to reliably differentiate between type 1 and type 2 diabetes.

Antibodies with a high diagnostic value are anti-GAD 65 (auto antibodies against glutamate decarboxylase), anti-IA 2 (autoantibodies against the protein tyrosine phosphatase IA 2, an Islet cell Antigen) and insulin antibodies.

Application
The main applications for identifying the autoantibodies involve early diagnosis of type 1 diabetes, the prognosis for first-degree relatives of people with type 1 diabetes and also the differential diagnosis of late overt diabetes or gestational diabetes.

Insulin antibodies, IA 2 and GAD 65 autoantibodies are rarely found at the same time, which means that these antibody determinations complement one another. Autoantibodies against IA 2 can be found, depending on the patients’ ages, in 50-70 % of newly diagnosed cases of type 1 diabetes. There is a high prevalence of IA 2 antibodies in children and young people, while IA 2 antibodies are found in less than 50 % of diagnosed cases in adults. For elderly patients, however, GAD 65 autoantibodies make differentiation between the late manifestation of type 1 diabetes (late autoimmune diabetes in adults, LADA) and type 2 diabetes possible, and they are also suitable – even years after the onset of the disease, e.g. after unsuccessful treatment in the form of a diet or therapy with oral antidiabetic agents – for identifying autoimmune diabetes.

Indication for anti-GAD, anti-IA 2 and insulin antibodies

  • Diagnosis of type 1 diabetes / differential diagnosis between type 1 and type 2 diabetes (anti-GAD 65, anti-IA 2, insulin antibodies)
  • Prognosis for first-degree relatives of type 1 diabetics (anti-IA 2)
  • Differential diagnosis in gestational diabetes (anti-GAD 65)
  • Prognosis for the clinical progression (insulin requirement) in the diagnosis of diabetes mellitus (anti-GAD 65, anti-IA 2, insulin antibodies)
  • Detection of late overt type 1 diabetes (LADA), (anti-GAD 65)
  • Progression to overt type 1 diabetes in healthy and young people (anti-IA 2)

Sensitivity: approx. 100 % for both parameters
Specificity: approx. 100 % for both parameters

Test material
1 ml of serum

Test principle
ELISA


Literature

1. Martin, S. and H. Kolb, Pathogenese und Immuntherapie des Diabetes Mellitus Typ 1, Diab. Stoffw.., 1998. 7: p. 17-242.
Verge, C.F., et al., Combined use of autoantibodies (IA 2 autoantibody, GAD autoantibody, insulin autoantibody, cytoplasmatic islet cell antibodies) in type 1 diabetes. Diabetes, 1998. 47 (12): p. 1857-66

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