Well-designed large-scale clinical trial has changed the management paradigms of type 1 diabetes (T1D). The Diabetes Control and Complications Trial (DCCT) and its follow-up study, Epidemiology of Diabetes Interventions and Complications (EDIC), established intensive management, which resulted in reduced risk for cardiovascular events among T1D patients. Clinical studies were performed to improve glycemic control and long-term outcome. The advent of new technologies enabled meticulous glycemic control with reduced hypoglycemia. Recently, Reducing with Metformin Vascular Adverse Lesions (REMOVAL) trial were published with mixed results. The results of several important studies will be summarized and discussed. To improve glycemic control and cardiovascular outcome of T1D, long-term follow-up study is required.