 To investigate the effect of rHuPH20, an adjuvant that accelerates the dispersion and absorption of subcutaneously injected or infused drugs, on mitigating post-prandial blood glucose excursions when injected separately or co-formulated with insulin during closed-loop therapy for youth and young adults with type 1 diabetes. Closed-loop control will be achieved using external subcutaneous real-time continuous glucose monitoring and continuous subcutaneous insulin infusion along with a computerized algorithm to link these two processes. 