Abstract: Objective To evaluate the recovery of island β-cell function through different terms of continuous subcutaneous insulin infusion(CSII)in diabetic patients with failure of oral hypoglycemic agents(OHA).Methods The 48 diabetic patients with OHA failure were divided into group A(10 cases,7-day CSII),group B(18 cases,14-day CSII)and group C(20 cases,28-day CSII).Results Compared with group A,the daily administration of basic dose and premeal supplementary dose of insulin at targeted glucose level were decreased in group B and C(P<0.05 and 0.01).The daily administration of total dose of insulin was significantly lower in group C than in group A(P<0.05).The first phase of insulin and peptide C secretion significantly improved in the group B and C versus group A(P<0.05 and 0.004).HbA1c significantly decreased in group A,B and C after CSII therapy,especially in group C(P= 0.004).During one year follow-up after CSII,the glucose level was controlled by OHA in 60% patients of group C.Conclusions CSII treatment for 4 weeks recovers the β cell function better than does CSII for 1-2 weeks