What are the benefits of treating anemia in people with diabetes?

Same as for nonDM: Pretty much same benefits as treating anemia in a non-diabetic. Less stress on heart, more energy. Only difference that might benefit diabetics may be more accurate a1c, as iron deficiency can make A1c less accurate.

Better health: Treating anemia typically leads to higher energy levels. The major question to answer is "what is the cause of the anemia?". This is critically important. For example, colon cancer causes a slow intestinal bleed can be a cause of anemia, and early detection of colon cancer makes a cure much more likely.