3507 – Medizym^® anti-GAD M

Highlights

• Use of recombinant human glutamic acid decarboxylase (GAD65)
• Ready-to-use (exception: wash buffer), color- and barcoded reagents
• Quality assured handling in routine laboratories
• Incubation at room temperature
• Quantitative determination of antibodies against GAD65)
• Calibrated with the international standard preparation NIBSC code 97/550
• Results expressed in IU/mL
• Excellent diagnostic sensitivity and specificity
• High precision within the measurement range
• CE marked
• Fully automatable

Intended Purpose

The Medizym^® anti-GAD M is a quantitative enzyme-linked immunosorbent assay for the determination of antibodies against Glutamic Acid Decarboxylase (GAD₆₅) in human serum. The Medizym^® anti-GAD M is intended as an aid in the diagnosis of diabetes mellitus type 1 , when used in conjunction with other clinical and laboratory finding. The immunoassay is designed for manual professional in vitro diagnostic use.

Diagnostic Relevance

Diabetes mellitus type 1 is a chronic autoimmune disease in which the immune system destroys the insulin-producing beta cells of the pancreatic islets of Langerhans. As a result, insulin production decreases, which in turn leads to elevated blood glucose levels characteristic of diabetes mellitus. Although genetic predispositions and viral infections are considered important risk factors, the exact causes remain incompletely understood.

In this context, islet cell antibodies (ICA) play a central role in destroying insulin-producing beta cells in the pancreas. Specifically, these antibodies target pancreatic islet antigens such as glutamic acid decarboxylase (GAD65), tyrosine phosphatase (insulinoma-associated antigen 2, IA2), the zinc transporter 8 (ZnT8), and insulin. Accordingly, clinicians detect islet cell antibodies in approximately 70–80% of patients with diabetes mellitus. Notably, these antibodies usually appear months to years before elevated blood glucose levels develop and therefore serve as important prognostic markers for identifying individuals at increased risk of developing type 1 diabetes. Consequently, at disease onset, clinicians commonly rely on the combined detection of antibodies against GAD65, IA2, ZnT8, and insulin as a key diagnostic approach.

From a biochemical perspective, glutamic acid decarboxylase (GAD) catalyzes the synthesis of the neurotransmitter GABA in the brain and in pancreatic beta cells. Two isoforms of this enzyme exist: GAD65, with a molecular weight of 65 kDa, and GAD67, with a molecular weight of 67 kDa. Most patients with type 1 diabetes mellitus, as well as many individuals in the prediabetic phase, develop antibodies against GAD65.. In contrast, patients with the rare neuromuscular Stiff-man syndrome produce antibodies against both GAD isoforms.

Publications

• Gonçalves et al., (2025) Comparison of assays for detection of neuronal surface autoantibodies