Therefore, it was postulated that salivary glands are subjected to the activity of autoimmune cells by direct action of antibodies against beta cells of pancreatic islets or specific antibodies against salivary gland antigens.[26] This hypothesis was supported by Markopoulos et al[30] noticed high levels of glutamic acid decarboxylase (GAD) antibodies in blood and saliva of children with type 1 diabetes against beta cell antigens, which indicates that submandibular duct cells may be the target of autoimmune attack against submandibular gland. This evidence concerns the gene GAD1 and type 1 diabetes mellitus.