Abstract: To detect the varying degree of deacetylation effect of chitooligosaccharides prepared by enzymatic hydrolysis on the proliferation of pancreatic islet cells、the release of insulin and 2 h plasma glucose in diabetic mouse induced by streptozotocin. Chitooligosaccharides were prepared by enzymatic hydrolysis. In vitro,the effect of varying degree of deacetylation chitooligosaccharides on the proliferation of pancreatic islet cells and the release of insulin were detected with optical microscope，MTT colorimetric assay，radioimmunoassay methods respectively; the general clinical symptom，2 h plasma glucose，urine glucose，oral glucose tolerance test were examined after 60 days feeding study to determine the effect of varying degree of deacetylation chitooligosaccharides on diabetic mouse induced by streptozotocin. The results indicate that the varying degree of deacetylation chitooligosaccharides can effectively accelerate the proliferation of the pancreastic β cells， chitooligosaccharides has prominent effect on the release of insulin.All varying degree of deacetylation chitooligosaccharides have effective effects on the general clinical symptom of DM rats,decrease the 2 h plasma glucose and urine glucose, normalize the disorders of glucose tolerance.

Key words: chitooligosaccharides; diabetic rats; 2 h-plasma glucose; oral glucose tolerance test; pancreastic islet cells; streptozotocin