The incretins are peptide hormones secreted from the gut in response to food. They increase the secretion of insulin. The incretin response is reduced in patients with type 2 diabetes, so drugs acting on incretins may improve glycaemic control. Incretins are metabolised by dipeptidyl peptidase, so selectively inhibiting this enzyme increases the concentration of circulating incretins. A similar effect results from giving an incretins analogue that cannot be cleaved by dipeptidyl peptidase. Studies have identified other actions including improvement in pancreatic beta cell glucose sensitivity and, in animal studies, promotion of pancreatic beta cell proliferation and reduction in beta cell apoptosis.