The present invention relates to the use of an extract of a plant selected from the group consisting of Psidium cattleianum, Psidium cattleianum ssp. Lucidum, Psidium guajava, Psidium guineense, Psidium littorale, Psidium molle and Psidium schiedeanum for the manufacture of a medicament for the treatment of a disease and/or condition related with and/or caused by activity of DP-IV or DP-IV like enzymes.