To the Editor In a Viewpoint article, Drs Lipska and Krumholz1 discussed the role of hemoglobin A1c (HbA1c) and how its incorporation into clinical guidelines and clinical trials is evolving. There is growing evidence that using glycemic control as a surrogate for preventing adverse outcomes related to diabetes may be inappropriate.2 As Lipska and Krumholz pointed out, 2 studies with empagliflozin (EMPA-REG OUTCOME)3 and liraglutide (Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results [LEADER])4 compared with placebo found a decrease in cardiovascular events and mortality. However, although the level of glucose control at the end of the studies was similar, control was not equal throughout the trials and representing it as such is somewhat inaccurate.
Venker BT. Hemoglobin A1c as a Surrogate for Clinical Outcomes in Diabetes Studies. JAMA. 2017;318(2):200. doi:10.1001/jama.2017.7222