Zizyphus is one of the plants commonly used in Egyptian folk medicine for the treatment of different diseases. The present study aims to investigate the effect of the butanol extract of Zizyphus spina-christi leaves as well as christinin-A, its principle saponin glycoside, in normal and streptozotocin-diabetic rats. In normal rats, treatment in both cases for one and four weeks produced insignificant changes in all studied parameters. However, in diabetic rats, both treatments significantly reduced serum glucose level, liver phosphorylase and glucose-6-phosphatase (G-6-pase) activities, and significantly increased serum pyruvate level and liver glycogen content after 4 weeks treatment. There was also marked improvement in glucose utilization in diabetic rats in both cases. Serum insulin and pancreatic cAMP levels showed significant increases in diabetic rats treated for a period of 4 weeks with the butanol extract.