In addition, iron deficiency anemia, characterized by Hb levels < 13 g/dL in men and Hb < 12 g/dL in women associated with low serum iron <7.1 μg/L, low serum ferritin <30 ng/L, low transferrin saturation percentage (<15%), and high total iron-binding capacity > 13.1 μmol/L, could overestimate HbA1c values [28,29,30,31]. This evidence concerns the gene GSTM1 and anemia.