SDC1 and Hyperglycemia: Synstatin, a peptide inhibitor of syndecan-1, suppresses endothelial cell migration and angiogenesis under vascular endothelial growth factor (VEGF) stimulation through incorporative communication between integrin, insulin-like growth factor 1 receptor, and VEGF receptor 2 [35], indicating that loss of syndecan-1 caused by hyperglycemia-induced oxidative stress may be involved in retinal endothelial dysfunction and microvascular abnormalities.