ObjectiveTo observe the effect of tacrolimus at different concentrations on the blood glucose in rats. Methods 30 male SD rats, weighing about 80 g, were randomly divided into three groups. Group A was given tacrolimus (Astellas Ireland Co., Ltd) 2 mg/kg per day and Wu Zhi soft capsules containing schizandrin A and other components (Sichuan Guangda Pharmaceutical Co., Ltd.) 0.2 / kg per day for 5 months. Group B was given tacrolimus 2 mg/kg per day for 5 months. Group C was used as control and received daily saline solution. The three groups of rats were administered orally in the fasting state. The tacrolimus plasma concentration and fasting blood glucose were monitored monthly. Results Blood concentration of tacrolimus of group A was significantly higher than that in the group B ( P <0.01). In the first two months of drug administration, there was no significant difference in fasting blood glucose among the three groups (P> 0.05). The Groups A and B had significantly higher blood glucose than in the group C three months after treatment (P <0.01) . In the last two months the blood glucose of the groups A and B continued to rise, and the blood glucose in group A was significantly higher than that in group B (P <0.01). ConclusionsTacrolimus causes elevated blood glucose by reducing insulin secretion and increasing insulin resistance. This glycemic effect is time-dependent and dose-dependent.