Adequate control of diabetic patients may not only delay the appearance of diabetic retinopathy, but may, moreover, effect the regression of fundus changes at the pre-retinopathic stage and in cases of commencing non-proliferative retinopathy. Medical treatment is based on the achievement of a decrease in vascular permeability and a lowering of the blood lipid level; a diet enriched with phosphates may influence retinal hypoxia by increasing the 2,3 diphosphoglycerate level in the erythrocytes, thereby leading to an improved free oxygen supply to the tissue. Complete medical and dietetic compensation of hyper-permeability of the retinal capillaries, of the intraretinal exudation of lipoproteins, and of retinal hypoxia belong still today to utopia; hence, conservative treatment is only of auxiliary character. Hypophysectomy has largely been abandoned in view of the mutilation involved and the poor results of this procedure. The most effective active treatment is photocoagulation. The best results are obtained by a combination of generalized unselective coagulation of the peripheral retina by means of a xenon coagulator and the selective elimination of progressive vascular changes seen in the fluorescein angiogram with argon laser.