Objective To investigate the effects of endogenous estrogen on blood glucose level,serum insulin level,and plasma total antioxidant capacity in streptozotocin-induced diabetic female mice,and to explore possible protective effects of estrogen on pancreatic islet cells.Methods Female mice were randomly according to body weight divided into four groups:( 1 ) Sham( Sham operation and vehicle administration) ; ( 2 ) Ovx( ovariectomy and vebicle administration ) ; ( 3 ) Sham + STZ ( Sham operation and STZ administration ) ; and ( 4 ) Ovx + STZ ( ovariectomy and STZ administration).The diabetic mice were induced by intraperitoneal injection of streptozotocin (STZ,50 mg/kg ).Blood glucose levels were measured once a week.Results The blood glucose level and malondialdehyde of Ovx group were higher than that in Sham group,while total anti-oxidant capacity ( T-AOC ) was lower than those in Sham group.the blood glucose level and MDA of Ovx+ STZ group were higher than those in Sham +STZ group,while T-AOC and serum insulin level were lower than those in Sham + STZ group.Conclusions Endogenous estrogen may have some protective effects on pancreatic islet function from streptozotocin-induced diabetes mellitus in female mice.