Van Bon et al. showed a mean TIR of 80% when adults with T1D used a fully closed-loop system with both insulin and glucagon over a period of 12 months (no comparator therapy) [127], while the iLet bi-hormonal system increased TIR compared to the single hormone (insulin-only) system (79% vs. 72%) and decreased TBR (2% vs. 4%) [128]. Here, GCG is linked to type 1 diabetes mellitus.