Incretins such as glucagon-like-peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) play crucial roles in postprandial glucose management. GLP-1 and GIP stimulate insulin release in conjunction with meals and are responsible for up to 75% of the insulin secretion. Incretins are therefore very important for maintenance of normal blood glucose levels. Dairy foods are crucial for adequate nutrition at a young age, and skim milk powder in infant formula is frequently used. However, stored skim milk powder has been found to reduce the islet cell mass of the pancreas in experimental studies. The aim of this study was to investigate the potential effect of stored skim milk powder on incretin release from intestinal cells. Intestinal endocrine cells (STC-1 cells) were incubated with fresh and stored skim milk powder, the latter containing 70-fold higher amounts of Maillard reactants. The cells' viability, proliferation, and release of incretins were measured after 24 h. Both the viability and proliferation of the STC-1 cells decreased significantly during incubation with stored skim milk powder. The release of GLP-1 and GIP was suppressed in a dose-dependent manner by stored skim milk powder compared with fresh milk powder. The clinical significance for the development of diabetes and obesity, due to this observed weak release of incretins induced by stored skim milk powder containing high amount of Maillard reactants, requires further studies.