ObjectiveTo investigate the expressions of glucose transporter-4 (GLUT-4) and secreted protein acidic and rich in cysteine (SPARC) in adipose tissue of Goto-Kakizaki (GK)/Wister rats after gastric bypass operation (GBP), and to explore the possible mechanism of GBP improving insulin resistance.MethodsHealthy male GK rats were randomly divided into diabetic operation group (DO group, underwent GBP), diabetic sham operation group (DS group, underwent sham-operation), and diabetic control group (DC group, received no-treatment), Wister rats were set as normal control group (NC group, received no-treatment). The weight, fasting blood glucose (FPG), fasting serum insulin (Fins), and HbA1c were measured before operation and at the 1st, 2nd, 4th, and 8th week after operation. Quantitative insulin sensitivity check index (QUICKI) was measured in before operation and at the 8th week after operation, and the expressions of GLUT-4 and SPARC protein in adipose tissues were measured by Western Blot method at the 8th week after operative too.Results① Weight: the weight of the DO group was lower than preoperative at the 2nd and 4th week after GBP (P<0.05), but increased to the normal level at the 8th week after GBP (P>0.05). The weight of the DO group was lower than those of the DS group, DC group, and NC group at the same time point of 2nd, 4th, and 8th week (P<0.05). ② FPG: the FPG level of the DO group was lower than preoperative at the 2nd, 4th, and 8th week after GBP (P<0.05), and lower than those of the DS group and the DC group from 2nd to 8th week after GBP (P<0.05). The FPG level between the DS group and the DC group had no statistical significance (P>0.05). ③ Fins: the Fins level of the DO group was higher than preoperative at the 2nd week after GBP (P<0.05), and decreased gradually at 4th and 8th week but not significantly differed from the NC group at the same time point. At the 2nd week after GBP, the Fins level of the DO group was higher than those of the DS group and the DC group (P<0.05), but there was no statistical significance between the DS group and the DC group (P>0.05). ④ HbA1c: the HbA1c level of the DO group started to decrease but there was no statistical significance between preoperative and all time after GBP (P>0.05). There was no statistical significance among the 4 groups at the 8th week after GBP (P>0.05). ⑤ QUICKI: at the 8th week, the QUICKI value of the DO group was higher than preoperative (P<0.05), and at the same time, the QUICKI value of the DO group and the NC group were higher than those of the DS group and the DC group (P<0.05), but there was no statistical significance between the DO group and the NC group (P>0.05), as well as the DS group and the DC group (P>0.05). ⑥ GLUT-4 protein and SPARC protein: the expression of GLUT-4 protein of the DO group was dramatically higher than those of the DC, DS, and NC group (P<0.05), and the expression of SPARC protein of the DO group was dramatically lower than those of the DC, DS, and NC group (P<0.05) at the 8th week. But the expressions of GLUT-4 and SPARC protein had no statistical significance among the DS, DC, and NC group at the 8th week after GBP (P>0.05).ConclusionGBP may improve and increase the sensitivity of insulin resistance by regulating the expressions of GLUT-4 and SPARC protein in adipose tissue of GK rats.