GCG and diabetes mellitus: The role of GLP-1 in glucose lowering that results from blunting glucagon signaling was investigated by Jun et al. (38) from the Eli Lilly and Co. laboratories using a double-knockout mouse model harboring deletion of both Gcgr and Glp1r. Similar to Unger’s findings, these studies showed that STZ-induced diabetes did not develop in Gcgr−/− mice.