Monitoring diabetic antioxidant status: a role for in vitro methaemoglobinformation

Diabetes leads to premature organ and system failure and considerably short ens lifespan. Careful control of glucose levels may not be enough to preven t the onset of complications in most diabetics. Compared with non-diabetics , diabetic tissues must not only resist a much greater long-term threat fro m hyperglycaemia-mediated reactive species but also defend themselves with compromised antioxidant systems. Although antioxidant therapy is a logical step in the prevention of oxidant and carbonyl stresses in the face of inte rmittent hyperglycaemia, this approach is not yet universally accepted to b e effective in preventing complications. Although there are many biochemica l indices of oxidant stress, piecemeal elevations of individual markers may not necessarily reflect true diabetic cellular antioxidant status. A dynam ic process such as in vitro methaemoglobin generation may provide an opport unity to compare the response of a diabetic erythrocyte with that of a non- diabetic before and after corrective antioxidant therapy. Due to compromise d cellular antioxidant capacity, diabetic cells generate less methaemoglobi n in the presence of aromatic amine hydroxylamines, 4-aminophenol and nitri te compared with non-diabetics. Agents such as dihydrolipoic acid have been shown to correct methaemoglobin formation-mediated thiol deficits during i n vitro studies. It is hoped that the progress of antioxidant supplementati on studies in diabetics can be monitored with the aid of in vitro methaemog lobin generation using agents such as hydroxylamines, 4-aminophenol and nit rite. The most appropriate antioxidants and dosages can thus be recommended to diabetics worldwide to attenuate the development of complications. (C) 2001 Elsevier Science B.V. All rights reserved.