To the Editor We appreciate the interest in and commentary on our published retrospective cohort study1 evaluating the association between preoperative metformin exposure and postoperative outcomes. We agree with George and Wren2 that individual low-risk medications with known adverse events (ie, metformin, statins, and β-blockers) or a combination therapy (ie, the polypill)3 may be the future of perioperative optimization. In our primary analysis, preoperative statin therapy was included in the generation of the propensity score, and statin therapy was well balanced between metformin exposure groups. In sensitivity analysis, statins were considered but not included in the multivariable model owing to both its lack of statistical significance and effect on the hazard of preoperative metformin exposure.