Autoantibodies against Glutamic Acid Decarboxylase (GADA), insulinoma antigen-2 (IA-
2A), insulin (IAA) and the most recently Zinc Transporter 8 (ZnT8A) are one of the most reliable biomarkers
for autoimmune diabetes in both children and adults. They are today the only biomarkers that
can distinguish Latent Autoimmune Diabetes in Adults (LADA) from phenotypically type 2 diabetes.
As the frequency of autoantibodies at diagnosis in childhood type 1 diabetes depends on age, GADA is
by far the most common in adult onset autoimmune diabetes, especially LADA. Being multiple autoantibody
positive have also shown to be more common in childhood diabetes compared to adult onset
diabetes, and multiple autoantibody positivity have a high predictive value of childhood type 1 diabetes.
Autoantibodies have shown inconsistent results to predict diabetes in adults. Levels of autoantibodies
are reported to cause heterogeneity in LADA. Reports indicate that individuals with high levels of
autoantibodies have a more type 1 diabetes like phenotype and individuals with low levels of autoantibody
positivity have a more type 2 diabetes like phenotype. It is also well known that autoantibody levels
can fluctuate and transient autoantibody positivity in adult onset autoimmune diabetes have been
reported to affect the phenotype.