The vitreoretinal relationships in 1021 eyes of 570 patients with diabetic retinopathy and in 857 normal eyes were studied retrospectively in an attempt to identify the vitreous changes specifically related to diabetes. Complete posterior vitreous detachment (PVD) occurred in diabetic patients largely as part of the aging process, but proliferation interfered with its development. Complete PVD with nonproliferative diabetic retinopathy in the younger age groups was more prevalent in eyes treated by panretinal photocoagulation (PRP) than in untreated eyes and thus might have an association with PRP treatment. Partial PVD, seen mainly in proliferative diabetic retinopathy, had no correlation with aging. In the eyes of patients who were younger when diabetes was diagnosed, the development of partial PVD had a close correlation with the duration of diabetes. The data suggest the need for a clinical trial of early photocoagulation, before partial PVD develops, in younger-onset diabetic patients showing early proliferative changes.