Gada

Anti-GAD antibodies are found in type 1 diabetes and Stiff-Man syndrome. GAD antibodies are directed against the glutamate decarboxylase GAD-65 in diabetes mellitus. High-titer GAD-65 antibodies can also be found in about 60% of patients with Stiff-Man syndrome. Antibodies against GAD-67 are found in Stiff-Man syndrome but not in diabetes mellitus type I.

Method: Enzyme Linked Immunosorbent Assay. Unit U/ml; reference range < 10.0 U/ml. Prevalence at first diagnosis: 65-80

Glutamate decarboxylases (GAD) catalyze the synthesis of gamma butyric acid from glutamic acid. The glutamate decarboxylase occurs in two isoenzymes with different molecular weights (65 kD and 67 kD, respectively). GAD-65 is mainly expressed in pancreatic beta cells, GAD-67 in neurons.

Anti-GAD antibodies are found in type 1 diabetes and Stiff-Man syndrome. GAD antibodies are directed against the decarboxylase GAD-65 in diabetes mellitus, and high-titer GAD-65 antibodies can also be found in about 60% of patients with Stiff-Man syndrome. Antibodies against GAD-67 are found in Stiff-Man syndrome but not in diabetes mellitus type I.

Diabetes mellitus type I; LADA type of diabetes; the very rare Stiff-Man syndrome.

GAD-AK may be detectable pre-symptomatically before diagnosis of diabetes mellitus type I. At the time of diagnosis, GAD-AK is found in about 70-90% of cases with diabetes mellitus type I. After clinical manifestation of diabetes mellitus, the detectability of GAD-AK decreases steadily. However, they remain detectable longer than islet cell Ac. GAD-AK can confirm autoimmune diabetes years after the onset of the disease. In diabetes mellitus type II, GAD-Ac is not detectable. The examination of GAD-AK is mainly indicated for suspected diabetes mellitus type I, LADA type diabetes mellitus or Stiff-Man syndrome.