Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are established therapeutic agents for metabolic disease, whereas the pharmacological use of native GLP-1 is constrained by its extremely short circulating lifetime. Alb8-GA, a G-related albumin-binding domain, binds human serum albumin (HSA) with high affinity. Here, we engineered a chimeric GLP-1 protein (GLP-1-ABD) by combining GLP-1 with a truncated Alb8-GA sequence. Following recombinant expression and purification, GLP-1-ABD was characterized using mass spectrometry, circular dichroism, fluorescence spectroscopy, dynamic light scattering, and one-dimensional proton nuclear magnetic resonance (1D 1H NMR). Size exclusion chromatography demonstrated association of GLP-1-ABD with HSA, while molecular modeling provided structural insight into the corresponding binding interface. In GLP-1R-expressing cells, GLP-1-ABD stimulated intracellular cyclic adenosine monophosphate (cAMP) accumulation, with an EC50 of 1.25 ± 0.16 nM, compared with 0.97 ± 0.14 nM for liraglutide (p = 0.15). Molecular dynamics simulations further indicated that the GLP-1 moiety maintained key receptor interactions despite fusion to the albumin-binding domain. In MIN6 cells, GLP-1-ABD enhanced glucose-stimulated insulin secretion and produced responses similar to liraglutide across most of the tested concentrations. In diabetic rats, GLP-1-ABD improved the glucose-response profile during oral glucose tolerance testing and increased circulating insulin relative to untreated diabetic animals (p = 0.03), while insulin levels did not differ significantly from those observed with liraglutide (p = 0.44). Collectively, these findings show that the truncated ABD fusion preserves GLP-1R agonist activity while enabling HSA association and supporting sustained glucose-lowering effects, thereby providing a basis for further pharmacokinetic and efficacy studies of GLP-1-ABD.
