A 58-year-old man with type 2 diabetes mellitus and heart failure with reduced ejection fraction (HFrEF, LVEF 32%) presents for optimization of guideline-directed medical therapy. He is already on an ACE inhibitor, β-blocker, and MRA. The antidiabetic drug class marked **D** in the diagram is now initiated. Which of the following best explains why this drug class has become a cornerstone of HFrEF management, independent of its glucose-lowering effect?