INS and type 2 diabetes mellitus: Another enzyme involved in catabolism of vasoactive peptides, which could play a pathogenetic role in MS, is represented by CD26/dipeptidyl peptidase IV (DPP4), which primarily regulates systemic glucose metabolism by catabolizing glucagon-like peptide-1, glucagon inhibiting peptide and glucagon influencing insulin sensitivity and type II diabetes mellitus pathogenesis.