2. Blinded, Randomized Treatment Phase: Following the stabilization phase, subjects will be randomly assigned to blinded treatment with either glucagon or placebo, which will be delivered for up to 48 hours with an OmniPod® infusion pump with the controller set to a starting basal rate for glucagon of 5 μg/kg/hr and GIR adjustments used to maintain euglycemia. After 48 hours of blinded treatment, all subjects will transition to open-label active treatment. However, if GIR reduction from baseline is < 20% at 24 hours, subjects will be transitioned early to the open-label phase.