In addition, in the studies by Gao et al. and Zhao et al. on type 2 diabetes mellitus (T2DM) patients, administration of propolis for 18 weeks caused a significant increase in serum GSH and total polyphenols in comparison to the control; however, the ferric-reducing ability of plasma (FRAP), superoxide dismutase (SOD), glutathione peroxidase (GPx), malondialdehyde (MDA) or Ox-LDL-C levels were not affected by propolis supplementation24,25. This evidence concerns the gene SOD1 and diabetes mellitus.