Without restoring glucagon counterregulation to hypoglycemia in T1D and advanced T2D, strategies for improving glycemic control, including the use of newer insulin analogues (Lane et al., 2017; Wysham et al., 2017) and continuous glucose monitoring (Heinemann et al., 2018; Lin et al., 2019), fail to eliminate the risk of clinically significant hypoglycemia (Rickels, 2019). The gene discussed is GCG; the disease is type 1 diabetes mellitus.