Most peptide or protein-based drugs like insulin require an injection for delivery. Alternatives routes of delivery could potentially improve treatment efficacy and clearly improve the patient's quality of life. Herein, we evaluated an electrospray delivery method for dosing insulin in rats. We found that an electrospray formulation of insulin in aqueous deoxycholic acid (DCA) was effective at transporting insulin into the bloodstream of rats and thereby lowering blood glucose. Our analysis indicated that the inclusion of DCA likely enables insulin uptake both by decreasing the particle size of electrosprayed droplets and by dissolving a layer of mucosal cells.