INS and type 2 diabetes mellitus: In the Wisconsin Epidemiological Study of Diabetic Retinopathy (WESDR) 4-year progression of diabetic retinopathy and progression to proliferative diabetic retinopathy was observed in 41.2 and 10.5% of subjects with Type I diabetes, 34 and 7.4% of insulin-treated patients with Type 2 diabetes and 24.9 and 2.3% of non-insulin treated patients, respectively [75].