Abstract: Objective To clone ABCa5(a member of ATP binding cassette transporters.A subfamily)gene fragments in diabetic rats supplemented with selenium and detect their expression levels in the rats.livers.Methods T he cDNA fragments isolated from the diabetic rats supplemented with selenium(Se)were cloned,sequenced and homologiously analyzed in order to observe the expression in livers of different groups.The RT-PCR of ABCa5 gene was made by using the primers desig ned.Results The indentity between Se-12 different cDNA fragment and ABCa5 gene was 99%.The result of RT-PCR showed that compared with normal control group(0.572 9±0.024 1),the ex pression levels of ABCa5 mRNA significantly decreased in diabetes mellitus(DM)(0.160 6±0.0075)and DM+Se groups(0.385 7±0.019 4)(P<0.05),the expression levels of ABCa5 mRNA in DM-Se group were higher than those of DM group,and all the differences had statistical signifi cance(P<0.05).Conclusion ABCa5 can regulate the occur rence and metabolism process of diabetes mellitus in some ways.Selenium supplementation could increase the expression level of ABCa5 mRNA in the livers of diabetic rats.It may be one of the mechanisms that selenium can improve the diso rders of glucose and lipid metatolism in diabetic rats.