OBJECTIVE： To investigate the effects of MTP gene polymorphism on the lipid-regulating effect of simvastatin in the treatment of T2DM complicating with lipid metabolism disorder. METHODS： 120 T2DM inpatients with hypercholesterolemia were selected from our hospital during Jun. to Dec. 2015 and given Metformin hydrochloride sustained-release tablets， Enalapril maleate tablets and Simvastatin tablets. PCR-RFLP was used to detect MTP G493T genotype. The levels of TG， TC， LDL-C and HDL-C were detected by AU 400 automatic biochemistry analyzer before treatment and the 4th week after treatment. The effects of different genotype on the change of blood lipid level was analyzed. RESULTS： Among 120 patients， the patients with MTP G493T GG， GT， TT genotypes accounted for 61.67％， 26.67％ and 11.67％， respectively， meeting Hardy-Weinberg balance （P＞0.05）. Before treatment， there was no statistical significance in TC， TG， LDL-C and HDL-C among different genotypes （P＞0.05）. After 4 weeks of treatment， the decrease of TC and LDL-C in TT genotype patients were lower than that in GG and GT genotype， with statistical significance （P＞0.05）. There was no significant difference in the decrease of TC and LDL-C between GT and GG genotype， the decrease of TG and HDL-C（P＞0.05）. There was no significant difference in the incidence of ADR among different genotypes（P＞0.05）. CONCLUSIONS： After simvastatin treatment， the improvement of TC and LDL-C in patients with TT genotype is poor. MTP G493T gene polymorphism may be associated with the lipid-regulating effect of simvastatin in the treatment of T2DM patients with lipid metabolism disorder.