BACKGROUND: To develop somatic gene therapy model for diabetes mellitus, it is the most important to control it by glucose concentration. In order to develop the myoblasts that produce insulin by glucose concentration, the transfection of genes of human insulin, rat glucokinase and rat GLUT2 was conducted using C2C12, the murine myoblast cell line. METHODS: pMLC-hINSmut plasmid vector to which human insulin cDNA was inserted in C2C12 cell line, pCB7/GLUT2 and pCB7/GK to which GLUT2 and glucokinase were inserted. Based on the inserted gene, C2C12/INS-GLUT2, C2C12/INS-GK and C2C12/INS-GK-GLUT2 were prepared. In each cell line, its mRNA and protein expression were measured. Also, the capability of producing insulin in low glucose (2.7 mM) and high glucose (25 mM) were compared. RESULTS: 1. It was observed that C2C12/INS-GLUT2, C2C12/INS-GK, C2C12/INS-GK-GLUT2 cell line expressed mRNA and protein of transfected genes, respectively. 2. As for the insulin production depending on the glucose concentration in C2C12/INS, it slightly increased from 0.049 +/- 0.003 micro U/10(6) cells/hr to 0.197 +/- 0.022 micro U/10(6) cells/hr. However, in C2C12/GK-GLUT2-INS, it showed the most evident increase: from 0.251 +/- 0.074 micro U/10(6) cells/hr to 1.325 +/- 0.221 micro U/10(6) cells/hr. 3. The expression of insulin gene decreased in proportion to the insulin production capability, reaching the minimum point at the 8th week. CONCLUSION: Genetically engineered murine myoblast secreted insulin depending on the glucose concentration in vitro and was able to cause its decrement when transplanted. However, it should be continued to study the method to maintain the consistent genetic expression in somatic cell therapy.