Female NOD/ShiLtJ mice 8 weeks of age were anesthetized with isoflurane. A small, vertical incision was made to expose the intact pancreas. Then, the exposed pancreas was placed on a 50 mm glass-bottom dish for imaging on an inverted microscope. Body temperature was maintained using heating pads and heating elements on the objective. The mouse received, via retro-orbital injection, Hoechst 33342 (1 mg/kg in PBS) to label nuclei, albumin-AF647 (1 mg/kg in PBS) to label vasculature, and 75 μL of 30 µM LUXendin551. Images were collected using a Leica SP8 microscope, equipped with a ×25/0.95 NA objective and Spectra Physics MaiTai DeepSee mulitphoton laser. Excitation was delivered at λ = 800 nm for Hoechst and Albumin-AF647, with signals collected at λ = 410-500 nm and λ = 550-590 nm, respectively. LUXendin551 was excited at λ = 1050, with signal collected at 650-700 nm. A conventional PMT was used for Hoechst, with a HyD detector used for Albumin-AF647 and LUXendin551. Blood was collected from the tail vein prior to and 30 min after LUXendin555 injection, and glucose was measured using an AlphaTrak2 glucometer. After imaging, unconscious mice are euthanized by cervical dislocation.