The effect of UCP2 and UCP3 on ATP concentrations varies depending on cell type.[1] For example, pancreatic beta cells experience a decrease in ATP concentration with increased activity of UCP2.[9] This is associated with cell degeneration, decreased insulin secretion, and type II diabetes.[9][11] Conversely, UCP2 in hippocampus cells and UCP3 in muscle cells stimulate production of mitochondria.[9][12] The larger number of mitochondria increases the combined concentration of ADP and ATP, actually resulting in a net increase in ATP concentration when these uncoupling proteins become coupled (i.e. the mechanism to allow proton leaking is inhibited).[9][12]