IAA is an autoantibody against endogenous insulin. It is the only specific antibody against islet β cells among diabetes-related antibodies. It is a marker of autoimmune β cell damage. The positive rate of IAA in newly diagnosed T1DM patients is 30% ~ 40%, and it has a very important predictive value for autoimmune diabetes, especially T1DM in children ^[1].

The presence of GADA suggests that islet beta cells are destroyed and partially lost their functions, which is an important index for distinguishing T1DM from T2DM. GADA has a high sensitivity of up to 70%-80% in the detection of T1DM ^[2-3] , and the antibody can be stable in the body for several years for a relatively long time, so it has a greater diagnostic value for adult delayed autoimmune diabetes.

The target antigen of IA-2A is protein tyrosine phosphatase (PTP). It can reflect the early onset of islet β cell damage with high specificity, and can be used to identify high-risk populations for early intervention ^[4].

ICA is an important serum diagnostic marker for T1DM through the recognition of GAD, IA-2 and other antigens ^[5]. The positive rate of ICA in new patients with T1DM is as high as 60%-90%, which can be used as an early detection indicator of the disease. ICA is currently considered to indicate autoimmune damage to islet beta cells, and when it is persistently positive or at high levels, it has a high predictive value for T1DM. ICA level decreases with the duration and age of onset of diabetes, which has a high diagnostic and prognostic value for diabetic patients and their first-degree relatives ^[6].