GSTM1 and diabetes mellitus: T2DM: type 2 diabetes mellitus, RBC: red blood cells, WBC: white blood cells, RDW: red cell distribution width, MPV: mean platelet volume, MCV: mean corpuscular volume, MCH: mean corpuscular haemoglobin, MCHC: mean corpuscular haemoglobin concentration, Hb: haemoglobin, HCT: haematocrit