Abstract: Based on the successfully establishment of hyperglycemia model by intraperitoneal injection of streptozotocin, 90 KM male mice were randomly divided into the normal, model, black tea treated (high, medium, low doses), fungus fermented black brick tea treated (high, medium, low doses) and metformin hydrochloride (n=10/each group) groups, and were continuously administrated for 28 days to study the hypoglycemic effects of black tea and fungus fermented black brick tea processed from the same batch of fresh leaves. The results show that compared with the normal group, the weight, water, diet and blood glucose levels of the model group were significantly different (P<0.01). The blood glucose level of the model group reached the standard of hyperglycemic index and indicates that the model was successful. Compared with the model group, the high dose of black tea treated group and fungus fermented black brick tea treated groups’ liver index were significantly decreased (P<0.05) and the pancreas index were significantly enhanced (P<0.05). The total cholesterols of the middle and high doses of black tea treated groups and fungus fermented black brick tea treated groups were significantly decreased (P<0.05), while the activities of superoxide dismutase and catalase were significantly increased (P<0.05). The blood sugar, triglyceride and malondialdehyde levels of black tea treated groups and fungus fermented black brick tea treated groups were significantly decreased in a dose-dependent manner (P<0.05). Besides, glucose tolerance, activity of glutathione peroxidase, insulin levels were increased significantly in a dose-dependent manner (P<0.05). The damaged structure of pancreas were repaired in black tea treated and fungus fermented black brick tea treated groups. Except for the low-dose black tea treated group, the hepatic glycogen level were enhanced in other black tea treated groups (P<0.05). Compared with the black tea groups, the high-dose fungus fermented black brick tea was significantly superior to the high-dose black tea in improving insulin level, blood sugar level, oral glucose tolerance, malondialdehyde level and liver glycogen level (P<0.05). The middle and high dose groups of fungus fermented black brick tea were also significantly superior to the middle and high dose groups of black tea in increasing the activities of catalase, superoxide dismutase and glutathione peroxidase. The results prompt that both the black tea and fungus fermented black brick tea could reduce the blood glucose of hyperglycemic mice, and fungus fermented black brick tea had better effects than black tea. The underlying mechanism needs further investigation.

Key words: black tea, fungus fermented black brick tea, hyperglycemia, model mice, hypoglycemic effect