Eurich et al note that observational data from Reduction of Atherothrombosis for Continued Health (REACH) that we published in the Archives1 complement previous studies, and they fear that obtaining a higher level of proof regarding the safety and perhaps the benefits of metformin in very high-risk patients is not achievable.
Roussel R, Bhatt DL, Steg PG, Reduction of Atherothrombosis for Continued Health (REACH) Registry Investigators. Levels of Evidence Needed for Changing Indications, Contraindications, and Food and Drug Administration Labeling: The Case of Metformin—Reply. Arch Intern Med. 2011;171(11):1042-1043. doi:10.1001/archinternmed.2011.225