NGF and diabetes mellitus: In this regard, we have recently demonstrated that early treatment (starting from the onset of diabetes at 3 weeks of age) with topical nerve growth factor (NGF) in the Ins2akita (Akita) mouse model of diabetes [14] allows us to prevent retinal neurodegeneration and, in the long run, the development of the microvascular stage of DR, suggesting that early retinal neurodegeneration is directly involved in the pathogenesis of DR and that neuroprotection can prevent the development of DR [15].