A systematic review and meta-analysis of long-term randomised trials of DPP-4 inhibitors on haemoglobin A1c (HbA1c) was conducted. Electronic searches were carried out on the following databases: MEDLINE, EMBASE, Scopus and Web of Knowledge to December 2013. Searches were supplemented by a review of trial registries and references from identified trials. Trials were included if they lasted at least 76 weeks, and had intermediate and final assessments of HbA1c. Citations and full-text articles were screened by two reviewers. A random effect model was used to pool data.