A 58-year-old man with type 2 diabetes mellitus, a prior myocardial infarction, and stable heart failure with reduced ejection fraction (EF 30%) is taking metformin and lifestyle measures. His A1C is 7.8%, BP is well-controlled, and LDL is at target on a high-intensity statin. Which additional agent is most appropriate to improve both glycemic control and cardiovascular outcomes?