INS and snowflake vitreoretinal degeneration: We focused on the insulin-insensitive GLUT2 and the insulin-sensitive GLUT4 in particular since GLUT4 has been implicated in other vascular diseases, such as diabetes-related cerebral small vessel disease (SVD; Vermeer et al., 2007; Palacio et al., 2014; Umemura et al., 2017).