IFNG and type 1 diabetes mellitus: During the course of the disappearance of β-cells, no lymphocyte infiltration was observed, unlike in type 1 diabetes (T1D) models such as nonobese diabetic (NOD) mice [20] or Biobreeding (BB) rats [21], but the concentration of interleukin-18 (IL-18), an inflammatory cytokine, transiently increased at 9 weeks, resulting in a corresponding increase in interferon gamma (IFN-γ) and nitric oxide (NO) production by spleen cells and peripheral leukocytes, respectively, as well as macrophage infiltration around the pancreatic islet tissue.