The purpose of this small, proof-of-concept, mechanistic study is to determine whether hybrid closed-loop insulin delivery can achieve sufficient hypoglycemia avoidance in patients with long standing type 1 diabetes experiencing hypoglycemia and symptom unawareness despite receiving intensive insulin therapy standard-of-care to improve glucose counterregulation against insulin-induced hypoglycemia. As it remains critically important to understand the potential physiologic benefits of hypoglycemia avoidance by means of a hybrid closed-loop system in this population, studying each well characterized subject as his/her own control by a within subject design should serve the study purpose, and has been the standard approach to assessing the effects of various approaches to hypoglycemia avoidance in patients with unawareness. The data generated will be available to power future randomized clinical trials to determine the comparative efficacy of emerging artificial pancreas and β-cell replacement approaches to achieve target glycemic control with amelioration of problematic hypoglycemia in type 1 diabetes.