Objective:To investigate the effect of gastric bypass on the expression of liver glucokinase(GCK) in non－obese Goto－Kakizaki (GK) type 2 diabetic rats. Methods:Twenty male GK rats and twenty male Wistar rats were randomly divided into four groups:GK operation group(GO group),GK sham operation group(GS group),Wistar operation group(WO group),Wistar sham operation group(WS group). There were 10 rats in each group. The fasting blood glucose and serum insulin levels were measured before operation and on the 1st,4th and 8th week after the operation. Liver tissues were harvested 8 weeks postoperatively and reverse transcriptase polymerase chain reaction was used to detect liver GCK mRNA expression after the operation. Results:The fasting blood glucose of GO group decreased as early as the 1st week after surgery,which decreased from preoperative (8.73 ± 1.30) mmol/L to (6.84 ± 0.89),(6.27 ± 0.93),(5.86 ± 0.57) mmol/L on the 1st,4th and 8th week postoperation (P < 0.05). The insulin level remained consistently higher in GO group with respect to GS group,but there was no significant change during the follow－up period. On the 8th week after surgery,the liver GCK mRNA level in GO group were significantly higher than GS group(P < 0.05). Conclusion:Gastric bypass can directly improve glucose metabolism in non－obese type 2 diabetic rats,the increased expression of liver tissue GCK mRNA might contribute to the hypoglycemic effect of the surgery.