GLP1R and type 2 diabetes mellitus: In recent years, pharmacology companies have devoted to the discovery and design of drugs for T2D treatment, e.g., Metformin, Sulfonylureas, Meglitinides, Thiazolidinediones, DPP-4 inhibitors, GLP-1 receptor agonists, etc. Metformin is the first-line medication for the treatment of T2D, working for lowering the production of glucose in liver and improving insulin sensitivity.