This document summarizes a systematic review of cost-effectiveness studies on drug therapy for diabetes mellitus. Thirteen studies from the UK, Canada, US and Germany on type 1 and type 2 diabetes were identified. Most studies found interventions like insulin glargine, insulin detemir, exenatide and rosiglitazone to be cost-effective compared to other treatments. However, limitations included heterogeneity between studies and inclusion of only English language studies. Future reviews should consider additional databases and languages.