P2RX4 and diabetes mellitus: Although previous studies on purinergic signaling in different organs (e.g., pancreas, brain, kidney, eyes, skin, bladders, and gastrointestinal organs)16 have been performed extensively in various immune disorders (i.e., SS and diabetes), studies targeting purinergic receptors, specifically P2X7R and P2X4R, in the SG of patients with diabetes remain scarce.