Objective: The Diabetes Control and Complications Trial (DCCT) demonstrated the powerlul impact of glycemic control on the progression of diabetic retinopathy. A large number of individuals (2,771) underwent stereoscopic color photography and fluorescein angiography as part of screening for participation in the DCCT. A subgroup of those individuals screened participated in the DCCT and underwent evaluation of their retinal vasculature semiannually for 4-9 years. These data were evaluated to determine how the 2000 American Diabetes Association position statement would apply to the DCCT experience. Specifically, the position statement indicates that the first dilated eye examination should be performed after 3-5 years' duration of diabetes because vision-threatening retinopathy virtually never develops in patients with type 1 diabetes during that interval
Research design and methods: We examined the experience of the DCCT in evaluating retinal photographs in 1,613 patients with type 1 diabetes of <5 years' duration and follow-up photographs every 6 months for 4-9 years in 855 members of that group.
Results: Of 1,613 subjects with type 1 diabetes of <5 years' duration screened for the DCCT, 716 (44.4%) had stereo-color photographic evidence of diabetic retinopathy, and 6 had preproliferative or worse pathology. Fluorescein angiography revealed retinopathy in 158 of 713 subjects with no evidence of retinopathy on color photographs. Thus, 874 (54.2%) of the original 1,613 subjects had retinopathy at baseline. DCCT follow-up identified 341 additional individuals in whom retinopathy was developing before 5 years; 1,083 of 1,613 (67.1%) individuals screened for the DCCT had retinopathy before 5 years' duration of diabetes. Those with retinopathy before 5 years had more rapid three-step progression of vascular pathology than those with no retinopathy.
Conclusions: Dilated eye examinations and retinal photography should be included in the routine management of type 1 diabetes during the first 5 years to identify the individuals at greatest risk for vision-threatening problems.