Objective: To investigate the relationship between early-onset retinopathy and urinary markers of renal dysfunction. Research Design and Methods: The Diabetes Incidence Study in Sweden (DISS) aims to register all new cases of diabetes in young adults (15-34 years). In 1987-1988, 806 patients were reported and later invited to participate in a follow-up study focusing on microvascular complications after ∼10 years of diabetes. In the present study, 149 patients with type 1 diabetes, completed eye examination, and urine sampling were included. Results: The patients with retinopathy (n=58, 39%) had higher HbA1c (P<.001) and urinary IgG2/creatinine (P<.05) and IgG2/IgG4 ratios (P<.05). Patients with maculopathy had the highest levels. No significant differences in urinary albumin/creatinine, glycosaminoglycans (GAGs)/creatinine, Tamm-Horsfall protein (THP)/creatinine, and IgG4/creatinine ratios were found. Women had higher urinary albumin/creatinine (P<.01) and urinary IgG2/creatinine ratios (P<.01) than men. Conclusions: Young adults with type 1 diabetes and early-onset retinopathy had higher IgG2/creatinine and IgG2/IgG4 ratios than patients without retinopathy indicating that retinopathy is associated with a change in glomerular size selectivity. This was found in association with normal urinary albumin and THP excretion and may be suspected to reflect early general vascular changes. © 2007 Elsevier Inc. All rights reserved.