GSTM1 and diabetes mellitus: Of the 209 participants with DM in this study, 139 (66.5%) were with SCT, while 70 (32.5%) were controls, and the mean age was 51.09 ± 14.4 years for the SCT group and 50.24 ± 12.4 for the controls; 44.6% were males in the SCT group, while they were 48.6% in the controls, with mean of Hb S 32.4 ± 4.7 in SCT group.