INS and type 2 diabetes mellitus: Moreover, vascular adipose tissues (VATs) of HFD-fed perforin−/− mice show overaccumulation of IFN-γ-producing CD4+ and CD8+T cells due to their increased proliferation and impaired AICD and M1-polarized macrophages due to a lack of cytotoxic action of the accumulated defective pro-inflammatory CD8+T cells, increasing insulin tolerance and predisposition to type 2 diabetes mellitus (T2DM) [511].