摘要:Recently some studies in diabetic rats or human showed that metformin treatment promote a reduction in glycaemia because by enhancing glucose uptake even in absence of insulin. There are evidences of relations among metformin, hexoquinase activity, glucose uptake and glycogen synthesis. The purpose of this study was to evaluate the muscle glycogen reserves of rats treated with microdoses of metformin after 15 days (1.6 ug.ml-1 or 3.2ug.ml-1). Our study showed that metformin 1.6 ug.ml -1 do not have effect on glycogen synthesis but metformin 3.2 ug.ml -1 increases in 78% (P<0,05) the muscle glycogen reserves. We did not observed hypoglycemic or hiperlactemic effect. It is concluded that micro dose of metformin (3.2ug.ml-1) increases glycogen content and could enhance exercise performance and changes exhaustion period.