The effects of sleeve gastrectomy on hormonal regulation of glucose metabolism in Goto–Kakizaki rats

BACKGROUND: The antidiabetic effect of sleeve gastrectomy (SG) has been interpreted as a conceivable result of surgically induced weight loss in the obese type 2 diabetes mellitus (T2DM) subjects. However, the blood glucose control often occurs within days, before significant weight loss has been reached. This work aims to investigate the major mechanism and persistence regarding how SG improves glucose metabolism in nonobese T2DM rats. METHODS: These Goto Kakizaki rats (n = 21) were randomly assigned into three groups: SG, sham SG, and pair-fed (PF) group, whose weight, food intake, oral glucose tolerance test, insulin tolerance test, plasma insulin, homeostasis model assessment for insulin resistance (HOMA-IR), ghrelin, and glucagon-like peptide-1 (GLP-1) were measured. RESULTS: According to the experiment, from the 2nd week until the 24th week, the fasting blood glucose of the rats in the SG group had significantly decreased with the improved glucose tolerance. At the 2nd week postoperation, the area under the blood glucose concentration curve (AUC) received a distinct reduction of 28.1 % (P < 0.0001). The ghrelin secretion of the SG group was significantly decreased (P < 0.005). The GLP-1 had increased (P < 0.0001), while the HOMA-IR values decreased (P < 0.05) throughout the experimental period. These effects were not seen in the sham-SG and PF groups despite similar changes of weight loss or food intake. CONCLUSIONS: The above results suggest that SG can conduct a direct control on T2DM instead of secondarily to weight loss or food intake around the whole experimental period. The changes of the gastrointestinal hormones may be the major mechanism of the antidiabetic effect.