GSTM1 and diabetes mellitus: Pearson’s analysis showed that there was a significant negative correlation between the RBC lifespan and AG level (r = −0.33; p < 0.0001) and glycosylated albumin (GA) and (r = −0.14; p = 0.010), respectively, while there was no significant correlation with age, HbA1c, duration of diabetes, or Hb (all p > 0.05), as shown in Table 2.