Until now the information from the sensor has been entered manually into the computer and the pump settings have also been changed manually. The investigators now need to move onto the next step which is to fully automate the system. The studies will be done in a clinical research facility. The investigators will study the young people on two nights in order to find out if the closed loop system started early in the evening is as effective as when it is started later before sleep. 12 young people will be recruited from diabetes clinics in the East Anglia region. The studies will provide further important information concerning the safety, efficacy and utility of closed loop systems.