CD4 and type 1 diabetes mellitus: T1DM is mostly characterized by an inflammatory lesion [31], which is infiltrated by helper T cells (CD4+ or Th cells), cytotoxic T cells (CD8+), B lymphocytes, and macrophages, eventually leading to the destruction of islet β cells [32, 33], and CD8+ cytotoxic T lymphocytes are the most frequent among the islet infiltrating immune cells.