This study is to explore the possible mechanism of ileal interposition (IT) treatment of glycemic control of the type 2 diabetes mellitus (T2DM) by establishing an IT animal model. Twelve T2DM rats (GK rats) of 8-week old were divided into GK IT surgery group (GK-IT) and GK sham group (GK-Sham). Six Wistar rats were used as the non-T2DM sham group (WS-Sham). Enzyme-linked immunosorbent assay was used to detect plasma insulin concentration and fasting pancreas glucagon-like peptide-1 (GLP-1) concentration changes. Homeostasis model assessment of insulin resistance was used to quantitatively measure insulin resistance. Glucagon-like peptide-1 receptor (GLP-1R) expression was detected by Western blotting. IT significantly decreased fasting blood glucose level and the oral glucose tolerance, and reduced insulin resistance of GK rats by increasing GLP-1 concentration and GLP-1R levels. The postoperative pancreatic beta-cell apoptosis rate of GK-Sham group was significantly higher than those in the GK-IT group and the WS-Sham group. IT significantly reduces blood glucose and decreases insulin resistance by upregulating GLP-1 concentrations and GLP-1R levels, which may contribute to insulin secretion of pancreatic beta-cells and decreases apoptosis of pancreatic beta-cell.