Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes mellitus (DM) and remains a major cause of visual impairment and blindness in adults. Accumulating evidence indicates that DR is not merely a microvascular disorder, but a complex neurovascular disease driven by long-standing hyperglycemia, metabolic dysregulation, oxidative stress, chronic inflammation, neurodegeneration, and impaired neurovascular coupling. Mitochondria are central regulators of cellular energy metabolism and redox homeostasis, and mitochondrial dysfunction is increasingly recognized as a pivotal mechanism linking hyperglycemia-induced metabolic abnormalities to retinal neurovascular unit injury. Under persistent hyperglycemic conditions, excessive glucose flux and metabolic overload promote mitochondrial reactive oxygen species (ROS) overproduction, mitochondrial DNA (mtDNA) damage, impaired oxidative phosphorylation, mitochondrial fusion-fission imbalance, defective mitochondrial biogenesis, dysregulated mitophagy, metabolic reprogramming, and epigenetic alterations. These abnormalities lead to ATP depletion, inflammatory amplification, and activation of multiple forms of programmed cell death, including apoptosis, ferroptosis, pyroptosis, necroptosis, and poly(ADP-ribose) polymerase 1 (PARP1)-dependent cell death. Mitochondrial injury affects retinal endothelial cells, pericytes, Muller cells, microglia, retinal ganglion cells, photoreceptors, and retinal pigment epithelial cells in a cell-type-specific manner, ultimately contributing to blood-retinal barrier disruption, capillary occlusion, neurovascular coupling impairment, retinal neurodegeneration, and progression from non-proliferative to proliferative DR. This review summarizes recent advances in mitochondrial dysfunction in DR, focusing on oxidative stress, mtDNA injury, mitochondrial metabolic reprogramming, mitochondrial dynamics, mitochondrial biogenesis, mitophagy, epigenetic regulation, mitochondria-associated cell death, and neurovascular unit dysfunction. Emerging mitochondria-targeted therapeutic strategies, including mitochondrial antioxidants, modulation of mitochondrial biogenesis and dynamics, mitophagy regulation, mtDNA protection, ferroptosis and inflammasome inhibition, epigenetic intervention, are also discussed. A deeper understanding of mitochondrial mechanisms may provide new therapeutic targets and translational opportunities for DR prevention and treatment.
