Methods for preventing beta cell degeneration, such as necrosis or apoptosis of beta cells in a subject, comprising administering a DPP-IV inhibitor to a subject in need thereof. The invention furthermore relates to a method for increasing the number and/or the size of beta cells. The invention also relates to a method for delaying the progression of Impaired Glucose Tolerance (IGT) to type 2 diabetes, as well as a method for delaying the progression of non-insulin demanding type 2 diabetes to insulin-demanding type 2 diabetes.