Abstract: Objective To investigate the association between a missense mutation (T/G, Ser 1369 Ala) in exon 33 of sulfonylurea receptor 1(SUR1) gene in type 2 diabetes patients and the glucose-lowering effect of Gliclazide. Methods 104 type 2 diabetes patients were selected and administered with Gliclazide orally for 56 days. Venous fasting plasma glucose levels (FPG), plasma glucose levels half an hour after taking 75g glucose (OGH) and two hours (OGT) after taking Gliclazide were measured. Ser1369Ala polymorphism genotypes(TT, TG, GG) of SUR1 gene were determined by Taqman method. 104 patients were grouped based on their different genotypes. The glucose-lowering effect of Gliclazide was compared among different groups. If FPG ★通讯作者：yangjk@trhos.com was reduced more than 20%, we took it as effective. People whose blood sugar level was effectively reduced and not effectively reduced were compared to see whether their genotype groups were different. Results The percent change of FPG，OGH and OGT on day one and day 57 among TT，TG and GG genotype groups had no statistically significant difference. Patients carrying one or two copies of the G allele displayed significantly larger percent decrease values of FPG (P＜0.05) compared with patients carrying the TT genotype. There was no statistically significant difference of the efficacy of Gliclazide in recessive model (TT+TG vs.GG). The combination of TG and GG was more effective in reducing blood sugar level than TT. Conclusion Patients carrying one or two copies of the G allele were more sensitive to Gliclazide than patients carrying T allele.