The skin is a component of the immune system. At a conceptual level, food antigen exposure to damaged skin can result in an immune response producing food allergy (FA). Food antigen exposure to healthy skin can produce a tolerogenic response, protecting against FA. Similarly, animal antigen exposure to damaged skin can result in an immune response producing autoimmunity due to molecular mimicry between human and animal proteins. Animal antigen exposure to healthy skin can produce a tolerogenic response protecting against autoimmunity. When the immune system encounters a protein in the absence of danger or damage associated signals, it learns to tolerate that protein. When the immune system encounters a protein in the presence of danger or damage associated signals, it treats the protein as being associated with a pathogen and learns to attack the protein. Live viruses or aluminum based adjuvants in vaccines provide the danger or damage associated signals. Therefore bovine insulin in milk protein containing vaccines and chick glutamate decarboxylase 65kDa (GAD65) in chick embryo cell culture protein containing vaccines cause the development of type 1 diabetes (T1D). Bovine adiponectin in milk protein containing vaccines can cause the development of type 2 diabetes (T2D), atherosclerosis related coronary artery disease, obesity, stroke, polycystic ovarian syndrome (PCOS), etc. Sequence homology between bovine, chick and human proteins are 87% for adiponectin, 76% for insulin and 95% for GAD65. Topical chicken protein and milk protein (say chicken broth + cow’s milk, applied to healthy skin) can help prevent, treat, or reduce medication requirements in T1D, T2D and other diseases above. Of course conventional treatment should continue until this epicutaneous immunotherapy (EPIT) takes effect. Anti-adiponectin and anti-insulin antibodies can also be of the IgG4 subclass. In such cases, a milk-free diet can help prevent, treat these diseases.