INS and diabetes mellitus: Diabetes is conventionally divided into: (i) type 1 diabetes mellitus (T1DM; autoimmune form) which is characterized by increased blood levels of autoantibodies directed against insulin-producing β-cells, and (ii) type 2 diabetes mellitus (T2DM; non-autoimmune form) which is characterized by increased peripheral resistance to insulin and decreased insulin secretion by pancreatic β-cells [3,5,6].