[Hypoglycemic effect of chitosan-microcapsulated insulin on the blood glucose level of streptozotocin-diabetic Wistar rats].

This study was conducted to observe the hypoglycemic effect of chitosan-microcapsulated insulin (insulin-microspheres) on blood glucose (BG), in diabetic rats by gavage. Using the scanning electron microscope, we observed the shape and distribution of insulin-microspheres in the tissues of liver, spleen, and small intestine of normal rats after gavage. The following groups of rats were studied: normal control rats (NC, n = 5); streptozotocin (STZ)-inducing diabetic control rats(DC, n = 6); STZ-diabetic rats treated with insulin-microsphere [120 u/kg] by gavage (DF, n = 6); STZ-diabetic rats treated with subcutaneous insulin injection [24 u NPH/kg] (DT, n = 6). Blood glucose was measured at 0-7 days after the treatments. The insulin-microspheres was found in small intestine, liver and spleen at 1, 2, 3 and 7 days. In DF group, the average blood glucose level decreased significantly from 24.7 +/- 3.2 mmol/L to 16.9 +/- 5.5 mmol/L during the first day of treatment and reached the lowest level (12.1 +/- 5.7 mmol/L) on the second day. From the third day on, the BG gradually elevated to the level before treatment; the maximum decrease of blood glucose level was 50.2%. In DT group, the average blood glucose level decreased from 25.2 +/- 3.8 mmol/L to 10.4 +/- 5.2 mmol/L during the first day of treatment and then went up gradually from the 2nd day on; the maximum decrease of glucose level was 58.7%. No significant difference was seen in maximum decrease between the two groups. These data demonstrate that oral chitosan-microcapsulated insulin has the antihyperglycemic effect on the blood glucose level of streptozotocin-diabetic rats.