Antioxidant effect of immediate- versus sustained-release melatonin in type 2 diabetes mellitus and healthy controls.

Oxidative damage has been suggested as the primary cause of aging and age-associated diseases including type 2-dependent diabetes mellitus (T2DM) and therefore there is a growing interest in exploring therapeutic potential of antioxidant agents including melatonin. In the present study, we analyzed red blood cell antioxidants and lipid peroxidation after 5 mg/daily immediate-release melatonin treatment of elderly T2DM patients and healthy elderly subjects in comparison with 2 mg/daily sustained-release melatonin treatment of elderly T2DM patients and healthy elderly subjects, to determine the antioxidant effect of different doses and formulations of melatonin in these groups. Our study revealed that there was no significant difference in antioxidant status of red blood cells measured by glutathione concentration and activities of GPx-1, CAT, GR, SOD-1 and MDA levels, after supplementation with 2 mg-sustained release melatonin or with 5 mg-immediate release melatonin, either in T2DM or in healthy elderly subjects. These results suggest that both preparations may exert similar therapeutic effect related to melatonin's action on antioxidant defense system.