A closed-loop insulin system, also referred to as the "artificial pancreas" (AP), is made up of an insulin pump, a continuous glucose monitor, and an application communicating between the two to adjust insulin administration based on glucose control. This is meant for the treatment of type 1 diabetes. The McGill Artificial Pancreas (MAP) has been used previously in type 1 diabetes with significant benefits. Though prior studies have shown significant benefit with this system, some challenges still exist. Semaglutide is used in type 2 diabetes and obesity; it is a once-weekly injectable medication that increases levels of a gut hormone called Glucagon-Like Peptide-1, which modifies gastric emptying, suppresses glucagon, and suppresses appetite. Though its use is not approved in type 1 diabetes in North America, it (along with similar drugs) has been used in studies as adjunctive therapy with insulin with benefits on blood sugar control. Similar medications have been used in type 1 diabetes (such as liraglutide and exenatide), but are not as strong in glucose effect even in type 2 diabetes as compared with semaglutide. The purpose of our study is to see if semaglutide administered weekly at the maximum tolerated dose in those with type 1 diabetes will have improved glucose control (as per time in target range from continuous glucose monitoring data) compared to placebo, while using a closed-loop insulin system.