NPY and diabetes mellitus: Elevated levels of glutamate are implicated in neurodegeneration and its toxic effects on the retina, particularly in RGC are well‐established.55, 56 In both human diabetes and experimental models of diabetes, glutamate levels are shown to be elevated.54, 57, 58 Expression of NPY in the mouse retina affords neuroprotective effects,26 confirmed by in vitro observations that rat retinal cells are protected from NMDA‐induced toxicity,59 although the NPY receptor subtype(s) involved in this neuroprotective effect remain unknown.