Interaction between pancreatic islets and vascular endothelial cells is necessary for the maintenance of beta-cell mass and function. Aside from acting as a conduit for molecular oxygen, vascular endothelial cells in vivo secrete the majority of islet extracellular matrix (ECM). This ECM likely provides a permissive signal for beta-cell proliferation, contributing to the coordinated hyperplasia of these tissues during the early stages of Type 2 diabetes. This ECM also provides a reservoir for heparin binding growth factors that further modulate this hyperplasia, including fibroblast growth factor (FGF) and vascular endothelial growth factor-A (VEGF-A). We hypothesize that communication between beta-cells and vascular endothelial cells directs the proliferation and function of both tissues.