The development of therapies for T1D has been neglected in favor of efforts in advancing therapies for the larger T2D population. Pharmaceutical companies have also been deterred by lack of clarity around the regulatory expectations for such therapies. The prospects for therapy for new-onset T1D have brightened in some respects because of convergence among regulators and clinical experts in views about how these therapies should be assessed. The most important consensus is that the primary efficacy end point for treatments directed at the underlying autoimmune cause of T1D should be endogenous insulin secretion, as reflected by standardized C-peptide measurements. Most T1D therapeutic development efforts are directed at new-onset disease, which represents a small proportion of the entire T1D population. A major deficiency in T1D therapeutic development is the lack of activity in advancing therapies for people with established T1D, a population that far outnumbers those with new-onset disease. Complete remission of new-onset or established T1D will almost certainly require a combination of two or more therapies to address the underlying cause of the disease and restore normal insulin function.