The local GLP-1 system in the olfactory bulb is required for odor-evoked cephalic phase of insulin release in mice

•The GLP-1/GLP-1R system in the OB promotes odor-evoked cephalic phase insulin release.•Obese mice lack odor-evoked CPIR.•Antagonizing GLP-1R by exendin-9 in the OB of lean mice inhibits CPIR.•Odor-evoked CPIR requires the activation of M3 muscarinic receptors.•GLP-1R in the OB controls olfactory-driven foraging.