 We hypothesize that; utilization of PH20 either as a separate injection PH20-preRx or in a co-formulation with insulin INS-PH20 during CL therapy will reduce peak-postprandial glucose concentrations and total glucose under the curve of the meal excursion as compared to CL control without any intervention, and we propose that the use of PH20-preRx and INS-PH20 will be well tolerated when delivered in youth and young adults in a closed-loop setting. 