Increasingly, we recognise that type 2 diabetes in youth is a disease with an aggressive time course and a significant complication risk. On the other hand, outcomes for youth with type 1 diabetes appear generally to be improving. With increasing numbers of both types of diabetes in youth, it is timely that a comparative perspective is offered to help clinicians prognosticate more appropriately. Contemporary comparative studies add a new perspective to a consistent story, that for youth-onset type 2 diabetes, the development and progression of cardio-renal complications are increased and the survival prognosis is significantly worse than for type 1 diabetes. Here, we review this mounting evidence, highlight the importance of metabolic syndrome factors in the excess risk and underscore that there remains a significant mortality gap for youth with either type of diabetes, to be addressed as a matter of urgency.