The authors demonstrated that the activated islet-specific CD8+ memory T cells were prevalent in T1DM patients with rapid disease progression, while the exhaustion-like profile of CD8+ memory T cells featuring the expression of multiple inhibitory receptors, including PD-1, limited cytokine production, and reduced proliferative capacity, was prevalent in T1DM patients with slow disease progression [42]. Here, PDCD1 is linked to type 1 diabetes mellitus.