Objective: To investigate the effect of gastric bypass procedure (GBP) on the secretion of the hormone of the “enteroinsular axis” and dipeptidyl peptidase-IV (DPP-IV) during exertion of its blood sugar-lowering action in rats with type 2 diabetes mellitus (T2DM). Methods: Twenty-four male spontaneous non-obese diabetic Goto-Kakizaki (GK) rats were equally randomized to undergo either gastric bypass surgery (GBP group) or sham operation (sham operation group). The body weight, fasting blood glucose, and the levels of DPP-IV and “enteroinsular axis” hormone glucagons-like peptide 1 (GLP-1) before and 1 week, 2, 4, 8, 12, 24 and 48 weeks after surgery of the two groups were recorded and compared. Results: The recorded parameters between the two groups had no obvious differences before operation (all P>0.05). The body weights of rats in both groups decreased significantly within the first week after surgery and then recovered gradually, but at each predefined time point, there were no significant differences between the two groups (all P>0.05). Compared with those before surgery, the levels of fasting blood glucose, and plasma DPP-IV and GLP-1 in sham operation group did not change after surgery (all P<0.01); while the fasting blood sugar and plasma DPP-IV significantly decreased and GLP-1 level significantly increased in GBP group (all P<0.01). In addition, the levels of fasting blood glucose, DPP-IV and GLP-1 between the two groups had statistical significance at each observation time point after surgery (all P<0.01). Conclusion: The blood sugar control effect of GBP may be associated with its increasing the GLP-1 level of the “enteroinsular axis” through inhibiting the DPP-IV activity.