The glucagon-like peptide-1 (GLP-1) receptor, an important target for the treatment of type 2 diabetes, has been shown to signal at the cell surface as well as in intracellular compartments. Here, we present two GLP-1 analogues with increased cyclic-AMP signaling duration compared to the native hormone. Despite similarly elevated cAMP activities, the two analogues show drastically different abilities to induce intracellular receptor trafficking. Structure-activity relationship studies show that a cyclic-beta amino acid at position 18 is critical for the prolonged signaling behavior we observed. Real-time resonance energy transfer experiments with labeled analogues suggest more sustained receptor association in live cells compared to GLP-1. Cryo-electron microscopy analysis reveals molecular level details of the interactions between the ligands and full-length receptor. Our results show that signaling duration and receptor internalization can be modulated independently and provide new tools to probe the spatiotemporal determinants of GLP-1R signaling.