GSTM1 and anemia (phenotype): Furthermore, various antihyperglycemic agents have been proven to impact the development or prevention of anemia—the long-term use of metformin contributes to a vitamin B12 deficiency and low levels of Hb, while, in contrast, the use of sodium-glucose cotransporter-2 inhibitors (SLGT2i) has been associated with beneficial effects such as an increased hematocrit and erythropoiesis [23,24,25,26,27,28].