Animals were humanely euthanized using cervical dislocation, before injection of collagenase 1 mg/mL (Serva NB8) into the bile duct. Inflated pancreases were digested for 12 min at 37 °C and islets separated using a Ficoll (Sigma-Aldrich) gradient. Islets were cultured in RPMI medium containing 10% FCS, 100 units/mL penicillin, and 100 μg/mL streptomycin. cAMP assays cAMP assays were performed in SNAP-GLP1R:HEK293 cells, as previously described. Briefly, cells were incubated with 10 nM GLP-1(7-36)NH2 alongside increasing concentrations of LUXendin for 30 min, before lysis and measurement of cAMP using a HTRF (Cisbio) assay, according to the manufacturer's instructions. All assays were performed in the presence of 100-500 µM IBMX to inhibit phosphodiesterase activity. pEC50 and pIC50 values were calculated using log concentration-response curves fitted with a three-or four-parameter equation.