Lu et al. (2013) found that CRYBB2 was significantly elevated in the retina after 1 month of diabetes in mice. A study also revealed that β-crystallin and γ-crystallin were up-regulated in rat’s retina with DR (Fort et al., 2009). Free fatty acid receptor 1 (FFAR1) is an important nutrient sensor of circulating lipids that controls retinal glucose entry to match mitochondrial metabolism with available fuel substrates. Activation of the Ffar1 impairs glucose entry into photoreceptors (Joyal et al., 2016). Here, FFAR1 is linked to diabetes mellitus.