In diabetes mellitus, the retina is exposed to fluctuations in blood glucose concentrations, presumed decreases in oxygen availability and other metabolic disturbances induced by the disease. These metabolic phenomena may play a role in diabetic retinopathy. To understand these processes better, we measured oxygen consumption in vitro in retinas from normal and diabetic rabbits and examined the effect of oxygen and glucose concentration on retinal respiration. Retinal oxygen consumption is decreased in diabetic retinas compared to normal rabbit retinas (0.56 +/- 0.09 ml of oxygen per min per mg dry weight in normal and 0.40 +/- 0.07 ml of oxygen per min per mg dry weight in diabetic retinas). Retinal oxygen consumption is elevated if the oxygen tension is raised above normal in both groups. Glucose concentration did not significantly effect the oxygen consumption of the retina in either group.