Provided is a method of treating or preventing diabetes in a subject comprising administering a therapeutically effective amount of (a) a compound of formula (I)or a pharmaceutically acceptable salt thereof, and (b) a DPP-IV inhibitor, to a subject that has or is at risk of having diabetes, whereupon diabetes is treated or prevented in the subject. The method optionally comprises administering a therapeutically effective amount of the compound of formula (I), or a pharmaceutically acceptable salt thereof, to the subject, in which the therapeutically effective amount is increased once or twice during the course of administration.
