Clinicians and patients with type 2 diabetes enjoy an expanding list of medications to improve glycemic control. With this expansion has come a flurry of concerns about the safety of these antihyperglycemic agents, concerns that affect judgments about the risk/benefit balance of therapy. Some of these safety signals have been identified through the synthesis of existing research evidence. Thus, it has become important for clinicians and clinical policymakers to understand the strengths and limitations of systematic reviews and meta-analyses in determining the safety of diabetes medications. In this paper, we highlight key safety concerns with diabetes medications and discuss the role evidence synthesis plays in each, with special attention to its strengths and limitations. © 2014 Springer Science+Business Media New York.