PDCD1 and type 2 diabetes mellitus: To study the phenotype of NKT-like cells in T2DM, we analyzed by flow cytometry the expression of the major co-activating receptors, i.e. NKG2D, NKp46, and CD27, the early activation marker CD69, and the inhibitory receptors Tim-3, LAG-3, NKG2A, PD-1, and TIGIT, in circulating NKT-like cells from T2DM patients and HC.