Clinical studies have suggested that VDR polymorphisms and vit D deficiency is related to the development and progression of several autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, and autoimmune endocrine disorders (e.g., Hashimoto thyroiditis, type-1 diabetes mellitus (T1DM), Addison’s disease, and Graves’ disease) [66]. This evidence concerns the gene VDR and type 1 diabetes mellitus.