Background: Considering that pre-diabetes is one of disorders that increases developing of diabetes, this study was performed to investigate the effect of L-Arginine supplementation on antioxidant enzyme activity, total antioxidant capacity, and body composition in patients with pre-diabetes.

Materials and Methods: A double-blinded randomized clinical trial was performed on 46 pre-diabetic patients. Patients in intervention (n=23) and  placebo groups received  3g/day L-arginine and placebo (three 1gr L-arginine capsules), respectively for 8 weeks. Anthropometric, body composition, and dietary intake assessments, and also biochemical tests were done at baseline and end of study. Total Antioxidant Capacity (TAC), glutathione peroxidase enzyme and superoxide dismutase activity were measured. Paired t-test, independent t-test and ANOVA were used to analyze quantitative variables.

Results: Thirty eight patients (19 subjects in each group) completed the study. After adjusting confounding factors, no significant difference in body composition, anthropometric indices and dietary intake was observed at the end of study (p<0.05 in all factors), but a significant difference in TAC level was observed in the intervention group at the end of study (p<0.001).

Conclusion: Supplemenation with 3gr/day L-arginine for 8 weeks led to raised serum TAC level without changes in body composition in pre-diabetic patients.