Monotherapy with metformin: Does it improve hypoxia in type 2 diabetic patients?

Metformin reduces blood glucose levels predominantly by inhibiting hepatic gluconeogenesis, although it also may enhance insulin receptor number or ac tivity. The full effects of metformin are still poorly understood. In this study the effects of metformin on plasma xanthine oxidase (XO) activity, th iobarbituric acid-reactive substance (TBARS), lactate and fructosamine conc entration as well as erythrocyte antioxidant enzyme activities were investi gated in 46 patients with type 2 diabetes mellitus. All parameters were mea sured simultaneously just before metformin therapy (T-0), 1 month (T-1) and 2 months (T-2) later. Results were compared with placebo and control group . We noted significant decrease in XO activity and in TBARS concentration ( p < 0.001) during monotherapy with metformin vs. placebo and T-0 group. A s ignificant correlation was observed between the activity of XO and the conc entration of fructosamine (p < 0.001). Erythrocyte glutathione peroxidase s howed significantly lower activity in T-2 group in comparison with To group (p < 0.01). It is known that diabetic patients produce more TBARS as a res ult of enhanced free radical generation the source of which may also be the large amounts of XO produced following the conversion of xanthine dehydrog enase in hypoxic diabetic tissues. Thus, our results indirectly suggest tha t metformin can reduce toxic tissue damage through the inhibition on XO act ivity.