INS and type 1 diabetes mellitus: 373 (Type 2 diabetes 114) adults with known retinopathy meeting study definitions of Type 1 diabetes (n = 259, diagnosis < 30 years, insulin within 1 year, weight < 120% desirable) or Type 2 diabetes (n = 114, diagnosis > 30 years and not on insulin or diagnosis > 40 years and weight 120% desirable)