Renal disease, particularly glomerulosclerosis, is a major cause of morbidity and mortality in patients with juvenile-onset diabetes mellitus. Signaled by the onset of proteinuria after 15 or more years of insulin therapy, progressive renal insufficiency due to glomerulosclerosis terminates in uremia within five years. Although some patients have benefited from chronic dialysis programs, the outcome in uremic diabetics has been considerably better if successful renal transplantation can be accomplished. Extrarenal complications of diabetes mellitus and recurrence of diabetic lesions in transplanted kidneys have hampered the recovery and rehabilitation of transplant recipients. Other renal diseases encountered in juvenile diabetics are reviewed.