Diabetes leads to a wide array of complications in humans, including kidney failure, vascular disease, peripheral nerve degeneration, and vision loss. Diabetic retinopathy causes blindness in more working-age people in the United States than any other disease and contributes greatly to blindness in the young and old as well. The increasing rate of diabetes occurring in our society can only bring about a further decrease in the visual health of this country unless new modalities are discovered to prevent and cure diabetic retinopathy. Breakdown of the blood-retinal barrier and the resultant vascular permeability remains one of the first observable alterations in diabetic retinopathy and strongly correlates with vision loss. In this article, we examine the molecular components that form this blood-retinal barrier and explore how changes in the production of growth factors in the neural parenchyma cause an increase in vascular permeability and contribute to retinal degeneration.