Peptide growth factors provide an important means of coordinating the growth of cells within tissues and organs. Although their role in controlling cell growth is not well understood, they have been implicated in derangements of cellular proliferation that occur in diabetes, e.g., mesangial cell hyperplasia and atherosclerosis. Because several growth factors have been structurally characterized and the cell types on which they act identified, research is focusing on developing model systems to determine whether they are involved in the pathogenesis of specific disease states. New techniques, i.e., in situ hybridization, gene transfection, and detailed structural analysis of proteins, have made it possible to define both changes in the relative abundance of specific growth factors and potential changes in their actions in specific disease states. These techniques are being applied in diabetes research and will make it possible to determine the alterations that have occurred in growth factor synthesis and growth factor-matrix protein interaction and cell-type-specific alterations in cell growth that occur after loss of normal glucose homeostasis. The findings from these types of analyses should lead to a better understanding of how the complications of diabetes develop and rational strategies to control their effects.