Is it true that sitagliptin (Januvia) preserves or increases pancreatic beta-cell function or quantity over a period of time?
—Shah Niranjan, MD, Roslyn Heights, N.Y.

Yes, there are data to suggest that the dipeptidyl peptidase IV (DPP-IV) inhibitors, which include sitagliptin, may preserve beta-cell mass to some extent. The implications of this fact for therapy in diabetes, however, are unclear. Some feel that DPP-IV inhibitors may one day have a use in new-onset type 1 diabetes to preserve residual beta-cell mass and function. Others feel DPP-IV inhibitors may have a use in prolonging islet-cell graft survival following islet-cell transplantation (Diabetes. 2009;58:641-651. Accessed June 5, 2009). What is clear is that the benefits of these agents over other oral therapies for type 2 diabetes based on a possible prolongation of beta-cell survival have not been established. The impact on cost, side-effect profile, and hemoglobin A1c are still the main factors I use in deciding on an agent in the treatment of type 2 diabetes.
—Lyle Mitzner, MD