Objective To observe the effects of tacrolimus on blood glucose, insulin, expressions of protein phosphatase 2A and P-AKT in rats in order to explore the mechanism of hyperglycemic action of tacrolimus. Methods Sixty male SD rats (body weight 89.83±4.44 g) were randomly divided into tacrolimus group (n=40) and control group (n=20). The rats in the tacrolimus group were administrated with tacrolimus 4 mg/kg daily. The rats in the control group were given the same amount of normal drinking water daily. The rat body weight, fasting blood glucose concentration and blood concentration of tacrolimus were measured monthly. All rats were killed at 5 months after the tacrolimus administration. The serum insulin levels were detected by radioimmunoassay method. The expressions of PP2A and P-AKT in liver tissues were assessed by immunohistochemistry. Results After two months of administration, the blood glucose levels in the tacrolimus group were significantly higher than those in the control group. The HOMA-IR in tacrolimus group was significantly higher than that in the control group P < 0.05). ISI was significantly lower than that in the control group (P < 0.05). Immunohistochemical examination showed that the expression of PP2A in hepatocytes in the tacrolimus group was increased compared with the control group, while expression of P-AKT in hepatocytes of the tacrolimus group was decreased than that in the control group. Conclusions Tacrolimus can induce necrosis of islet cells, decrease of the amount of islet cells and insulin secretion, decease of sensitivity to insulin, and increase the resistance to insulin, therefore, leading to increase the blood glucose level in rats. The expression of PP2A in hepatocytes in the tacrolimus group is increased, while the expression of P-AKT is decreased. Interfering of insulin signal transduction pathways may be involved in the hyperglycemic effects of tacrolimus.