GSTM1 and type 2 diabetes mellitus: Among the three groups, the T2DM with anemia group was older than the control group and the T2DM without anemia group; Hb (107 g/l ± 12 vs. 142 g/l ± 13 vs. 139 g/l ± 12) and eGFR were significantly lower in the T2DM with anemia group than in the other two groups, while for the above three indices, the T2DM without anemia and the control groups did not show significant differences (all P < 0.001).