The four-year incidence and progression of retinopathy were investigated in a population-based sample of people with diabetes diagnosed at 30 years of age or older. For insulin users, 73 (47%) of the 154 who did not have any retinopathy at the first visit developed it in the four-year interval, and 31 (7%) of the 418 free of proliferative retinopathy developed it. Worsening of retinopathy occurred in a total of 34% (142/418). For nonusers of insulin, corresponding rates were 34% (110/320) for incidence of any retinopathy, 2% (11/486) for developing proliferative retinopathy, and 25% (121/486) for worsening. These population-based data clearly indicate the risk of retinopathy worsening in a short interval (four years) in a large proportion of people with older-onset diabetes, a group previously thought to be relatively protected from retinopathy. Such patients who make up the largest proportion of diabetic patients in the United States need examination when diabetes is first diagnosed and regular follow-up.