Poor medication adherence in patients with type 2 diabetes mellitus has become one of the main causes of suboptimal glycemic control. Once-weekly drugs can markedly improve the convenience, adherence, and quality of life of T2DM patients; thus, they are clinically needed and preferred. PTP1B plays a negative role in both insulin and leptin signaling pathways, which makes it an important target for diabetes. Herein, we design and synthesize 35 analogues of core BimBH3 peptide via lipidation/acylation strategy based on our previous work and evaluate their PTP1B inhibitory activity, obtaining the primary structure-activity relationship. Five compounds with good PPT1B inhibitory activity, target selectivity, and significantly improved stability were selected for molecular docking study and searching candidate molecules with long-acting antidiabetic potential. The in vivo anti-T2DM evaluation validated the once-weekly therapeutic potential of analogues 19, 26, 27, 31, and 33, which were comparable with semaglutide and therefore presented as promising drug candidates.