In the TREAT trial, which was the largest RCT and was published in 2009 [7], 4038 patients with diabetes, CKD and anaemia were randomly assigned to achieve a Hb level of ∼130 g/L with the use of darbepoetin alfa or placebo (patients in the placebo group received darbepoetin alfa as a rescue agent if Hb <90 g/L). This evidence concerns the gene GSTM1 and diabetes mellitus.