GCG and type 2 diabetes mellitus: Recent studies have reported that pancreatic β cells become dedifferentiated and convert to other endocrine cells under certain circumstances (Chakravarthy et al., 2017; Thorel et al., 2010) Consistently, we demonstrated that Angll efficiently induces the conversion of β cells into glucagon-producing α-like cells in db/db mice, which might explain the phenomenon that patients with type 2 diabetes are more likely to have elevated plasma glucagon levels and a glucagon-to-insulin ratio (Dunning and Gerich 2007).