Melatonin improves oxidative stress parameters measured in the blood of elderly type 2 diabetic patients

An elevated oxidative status in the aging organism may be involved in the development of non-insulin dependent diabetes mellitus (NIDDM). Melatonin, a potent antioxidant agent, is essential for glucose homeostasis and regulation. The aim of this study was to determine the influence of melatonin supplementation on the oxidative stress parameters in elderly NIDDM patients. The malondialdehyde (MDA) concentration, Cu-Zn superoxide dismutase (SOD-1) activity in erythrocytes, the level of nitrate/nitrite in plasma and morning melatonin concentration and oxidase activity of ceruloplasmin (Cp) in serum in 15 elderly NIDDM patients at baseline and after the 30 days of melatonin supplementation (5 mg daily) in comparison with levels in 15 healthy elderly volunteers were determined. A significant increase of MDA level and decrease of SOD-1 activity and melatonin concentration were observed in NIDDM patients. Cp oxidase activity and nitrate/nitrite level were similar in both examined groups. Melatonin administration in NIDDM patients resulted in a significant increase in the morning melatonin concentration and SOD-1 activity, and a reduction in the MDA level and Cp oxidase activity. Statistically significant alterations in nitrate/nitrite levels were not observed. These results indicate an improvement of antioxidative defense after melatonin supplementation in the NIDDM individuals and suggest melatonin supplementation as an additional treatment for the control of diabetic complications.