Comment on "Glutathione peroxidase activity in obese and nonobese diabetic patients and role of hyperglycemia in oxidative stress".

Madam,

We read with great interest the article by Goyal et al, dealing with an association between diabetic patients with obesity and decreased oxidative stress, and the effect of insulin treatment duration on oxidative stress at 24th and 48th weeks.[1] The authors revealed that oxidative stress analyzing with glutathione peroxidase levels were lower in diabetic patients with obesity than in nonobese diabetic patients and healthy subjects. In our opinion, some points of this work are not sufficiently clear.

First, measuring different oxidant and antioxidant molecules is impractical, and their oxidant and antioxidant effects are additive. Since there are numerous oxidants and antioxidants in the body, measuring total oxidant-antioxidant status is more valid and reliable. When only a few parameters are measured, their levels may be unchanged or decreased, even when the actual oxidant status is increased, or vice versa.[2] The authors have analyzed only glutathione peroxidase levels in their study, these levels can not demonstrate the total oxidative status in the study population. Further, levels of antioxidants have not been analyzed and compared.

Second, the authors have compared the duration of insulin treatment on glutathione peroxidase levels at 24th and 48th week, and Paired T test was used for the comparisons. The statistical methods for comparing these levels among them should be repeated measures of ANOVA. This method could have given the better results to demonstrate the effect of insulin treatment.

Finally; the demographical, anthropometric and laboratory parameters have not been given in the results part, shown of them either in the results part or in a table could have been better, too.

We hope that the above-mentioned items might add to the value of the article by Goyal et al.[1]