Abstract: This study for the first time is to examine the hypoglycemic effects of Platycodon grandiflorum (Jacq.) A. DC in streptozotocin (STZ) -induced diabetic ICR mice. The effects of P. grandiflorum ethanol extract (PGE) on blood glucose, exogenous insulin sensitivity and plasma insulin levels were investigated. In four doses of extracts from the root of P. grandiflorum, extract at dose of 100mg/kg significantly suppressed the rise in blood glucose after 30min in the acute glucose tolerance test. Furthermore, this dose was applied in the fellow experiments. A significant decrease in blood glucose levels was observed after treatment of PGE. A combination of PGE and glibenclamide produced a greater effect in blood glucose level than using glibenclamide or PGE alone. PGE enhanced and prolonged the hypoglycemic effects of exogenous insulin on diabetic mice. Plasma insulin levels were increased with glibenclamide treatment in diabetic mice, whereas such effect was not observed with PGE. These results indicated that P. grandiflorum enhances the hypoglycemic effects of exogenous insulin without stimulating insulin secretion, indicating that insulin sensitivity is increased in diabetic mice.

Key words:  , Platycodon grandiflorum A.DC.； diabetes mellitus； blood glucose； insulin；