We examined the effect of experimental diabetes on neurite regeneration from adult mouse retinal explants cultured in the presence of different concentrations of glucose. The numbers of regenerating neurites at 3, 6 and 10 days in culture at normal glucose concentration (7 mM) were significantly smaller in streptozotocin-induced diabetic C57BL/6 mice than in normal control mice. In contrast, treatment of retinal explants with high glucose concentration (57 mM) significantly diminished the number of regenerating neurites in the control mice, but not in the diabetic mice. These results suggest that retina in diabetic mice has impaired capability of neurite regeneration in a normal glucose environment, but is adaptable to a high glucose environment in vitro.