This test detects the presence of glutamic acid decarboxylase 65 (GAD-65) IgG antibodies in the blood. GAD-65 is an enzyme found in pancreatic beta cells, and the presence of these antibodies is commonly associated with autoimmune diabetes (Type 1 diabetes) and other autoimmune conditions. The test helps in diagnosing autoimmune-mediated diabetes, distinguishing between Type 1 and Type 2 diabetes, and assessing risk in individuals with a family history of autoimmune disorders.