DLG3312 is a dimer of GLP-1 via covalent linkage by a lysine. DLG3312 remains the native GLP-1 bioactivity and exhibits strong stability in vitro. DLG3312 can efficiently reduce the blood glucose on type 2 diabetes mellitus model mice. The efficacy of DLG3312 in mice is similar to a long-acting marketed drug liragutide.