Bariatric surgery enhances splanchnic vascular responses in patients with type 2 diabetes

Bariatric surgery results in notable weight loss and alleviates hyperglycemia in patients with type 2 diabetes (T2D). We aimed to characterize the vascular effects of a mixed meal and infusion of exogenous glucose-dependent insulinotropic polypeptide (GIP) in the splanchnic region in 10 obese patients with T2D before and after bariatric surgery and in 10 lean control subjects. The experiments were carried out on two separate days. Pancreatic and intestinal blood flow (BF) were measured at baseline, 20 min, and 50 min with 15O-water by using positron emission tomography and MRI. Before surgery, pancreatic and intestinal BF responses to a mixed meal did not differ between obese and lean control subjects. Compared with presurgery, the mixed meal induced a greater increase in plasma glucose, insulin, and GIP concentrations after surgery, which was accompanied by a marked augmentation of pancreatic and intestinal BF responses. GIP infusion decreased pancreatic but increased small intestinal BF similarly in all groups both before and after surgery. Taken together, these results demonstrate that bariatric surgery leads to enhanced splanchnic vascular responses as a likely consequence of rapid glucose appearance and GIP hypersecretion.