Our studies with retinal vascular cells have shown that HG-induced mitochondrial fragmentation (Figure 2) concomitant with altered membrane potential heterogeneity, reduced oxygen consumption rate, increased extracellular acidification, and that cytochrome c release promotes apoptosis, suggesting that mitochondrial dysfunction involving structural changes can mediate the retinal vascular cell death seen in diabetic retinopathy [1,2]. This evidence concerns the gene CYCS and diabetic retinopathy.