Objective  To explore effects of Jerusalem artichoke polysaccharide (JAP) on morphology and function of islet cells of type II diabetes rats and the mechanism of the effects.

  Methods  Type 2 diabetes mellitus (T2DM) rat model was established by feeding the Wistar rats with high-fat feeds combined with the administration of small dose of streptozotocin (STZ); the rats with routine feeds were used as a normal control group. Then the T2DM model rats were randomly assigned into a positive control group administered with dimethyldiguanide, three JAP groups administered with JAP at the dosages of 20, 40, and 80 mg·kg^–1, and a model group treated with double distilled water; all the administrations were performed via gavage once a day continuously for 8 weeks. Fasting plasma glucose (FPG) and fasting insulin level (FINS) of all the rats were measured at the end of the treatments. The morphologic changes of pancreatic tissue was observed with hematoxylin-eosin staining and the expression of insulin of pancreas cells of the rats was detected with immunohistochemical method.

  Results  Compared with those of the normal control rats, the FPG of model rats (18.24 ± 1.32 mmol/L) was significantly increased but the FINS (14.89 ± 1.76 ng/mL) was decreased significantly (both P < 0.05). Compared with those of the model rats, the FPG was significantly decreased to 10.77 ± 0.12 mmol/L and 8.56 ± 1.45 mmol/L for the rats treated with 40 and 80 mg·kg^–1 JAP (both P < 0.05); while the FINS was significantly increased to16.46 ± 1.88 ng·ml^–1 for the rats treated with 80 mg·kg^–1 JAP (P < 0.05). Alleviated pathological changes and increased insulin expression were observed in the pancreatic tissues of the rats treated with JAP.

  Conclusion  JAP has hypoglycemic effect through reducing insulin resistance, alleviating damage of islet β cells, and increasing the expression of insulin in rats with type type 2 diabetes mellitus.