OXIDATIVE STRESS IN DIABETIC MACROVASCULAR DISEASE - DOES HOMOCYSTEINE PLAY A ROLE

Background. Non-insulin-dependent diabetes mellitus (NIDDM) and hyperh omocysteinemia are both associated with increased lipid peroxidation ( oxidative stress). This may contribute to the accelerated Vascular dis ease associated with these conditions. It is not known whether the coe xistence of elevated homocysteine levels will stimulate oxidative stre ss further than that caused by diabetes alone. Methods. Plasma concent rations of thiobarbituric acid reactive substances (TBARS), an index o f lipid peroxidation, were measured in patients with NIDDM who had pre viously had a methionine load test; some of the patients had hyperhomo cysteinemia. Results. Plasma TBARS concentrations were elevated in dia betics with vascular disease. The additional presence of hyperhomocyst einemia was not associated with a further increase in plasma TBARS con centrations. Conclusions. Lipid peroxidation is increased in patients with diabetes mellitus and macrovascular disease and is not further el evated by the coexistence of elevated homocysteine levels. It is possi ble that diabetes maximally stimulates oxidative stress and any furthe r acceleration of vascular disease in patients who have coexistent hyp erhomocysteinemia is mediated through mechanisms other than lipid pero xidation.