GCG and type 2 diabetes mellitus: Studies on host-microbiome interaction through bacterial-derived proteins have discovered that a novel protein P9 secreted by Akkermansia muciniphila binds to host ICAM-2, thereby increasing the secretion of glucagon-like peptide 1 (GLP-1), suggesting that the interaction between P9 and ICAM-2 could be a potential therapeutic target in type 2 diabetes patients (1).