Complications of diabetes include retinopathy, nephropathy, neuropathy, macrovascular disease, and associated autoimmune diseases. Clinical manifestations of complications uncommonly present in childhood and adolescence. Screening during the early years can identify subclinical disease and it offers an opportunity for early intervention. The Diabetes and Complications Control Trial has provided evidence for the long-term benefits of good glycemic control in preventing and delaying the onset of microvascular complications. Complications begin to manifest during adolescence, during which time all efforts should be made to educate and support young persons in achieving optimal diabetes control.