Autoantibodies to Glutamate decarboxylase (GADA) have become the most commonly used predictive marker for type 1 diabetes. They were first associated with type 1 diabetes in 1990 through comparison of sera from patients with type 1 diabetes and stiff person syndrome. After IAA, GADA are the antibodies detected most often at seroconversion in infancy, with an incidence exceeding IAA in later childhood. They also persist into adulthood and act as a marker for adult-onset autoimmune diabetes. Most studies have indicated that GADA are more persistent in long-standing diabetes patients than IA-2A or ZnT8A. Glutamate decarboxylase (GAD) is found in neurons and the pancreas, where it is involved in the synthesis of gamma-aminobutyric acid (GABA).