Thus, deletion of IL-33 in the retina during diabetes may disrupt glutamate clearance, neurotransmitter recycling and the secretion of neurotrophins (Barnett et al., 2001; Gionfriddo et al., 2009; Bringmann et al., 2013), and this leads to lower ERG a- and b-wave amplitudes, retinal neuronal thickness, and numbers of photoreceptors and ganglion cells during diabetes. Here, BDNF is linked to diabetes mellitus.