HP and type 1 diabetes mellitus: The family of zonulin are proteins connected architecturally and functionally to pre-haptoglobin (HP) 2 and its mature isoform HP2, being the first constituent discovered and expressed only in individuals carrying the HP2 allele, with a fundamental role in chronic inflammatory diseases or autoimmune, such as CD and T1DM, caused by the loss of zonulin-modulated small intestine epithelial barrier and contributing to innate intestinal immunity [137,138,139,140,141].