Metformin decreases platelet superoxide anion production in diabetic patients

Background Patients with type 2 diabetes mellitus are usually treated with oral antidiabetic agents but it is still not known whether these drugs have antioxidant effects in humans. Methods We studied 60 patients with type 2 diabetes mellitus, divided into three groups on the basis of hypoglycaemic treatment (Group A: metformin, Group B: glibenclamide, Group C: diet). All patients were followed for at least 1 year. The three subgroups had similar clinical characteristics. Twenty healthy subjects, of comparable sex and age, were enrolled as controls. In each subject, platelet production of superoxide anion (O 2 − ) elicited by collagen, was determined by lucigenin assay. Results Patients with diabetes had higher platelet O 2 − production than controls; no correlation was observed between blood glucose and platelet O 2 − production. Group A patients had platelet O 2 − production similar to that of healthy subjects but lower than Group B and Group C patients. Conclusion The present findings suggest an in vivo antioxidant activity of metformin and warrant prospective studies to further explore this hypothesis. Copyright © 2002 John Wiley & Sons, Ltd.