Abstract： Objective To investigate the influence of insulin pump on type 2 diabetes mellitus.Methods 51 patients were randomized into two groups: 31 cases controlled with insulin pump,20 treated with oral antidiabetic drugs.Serum level of C-peptide concentration was observed.Results There was a markedly increase in C-peptide level in both insulin treating group(P<0.001) and oral drug group(P<0.01).Half an year later,the insulin group was improved in β-cell function better than oral drug group.Conclusions Several days controlling of severe hyperglycemia with insulin pump could not eliminate the β-cell inhibition of glucose toxicity.Newly diagnosed severe type 2 diabetes(FPG≥14 mmol/L) could be treated with insulin for several months.