The Effects of Bariatric Surgery on Pancreatic Lipid Metabolism and Blood Flow

Context: Bariatric surgery leads to a rapid and sustained weight loss often accompanied with improvement in glucose homeostasis. Objective: The objective of this study was to investigate the effects of bariatric surgery on pancreatic lipid metabolism, blood flow, and glycemic control. Design: This was a longitudinal study. Setting: The study was conducted in a clinical research center. Participants: This study included 27 morbidly obese and 15 healthy control subjects. Interventions: Measurements were performed using positron emission tomography with the palmitate analog 14(R,S)-[18F]fluoro-6-thia-heptadecanoic acid and radiowater ([15O]H2O) and computed tomography. In morbidly obese subjects, positron emission tomography/computed tomography imaging studies were performed before and 6 months after bariatric surgery (either Roux-en-Y gastric bypass or sleeve gastrectomy). Main Outcome Measures: Pancreatic fat and fat-free volume, fatty acid uptake and blood flow were measured as well as parameters of β-cell function, glucose tolerance, and insulin sensitivity. Results: Six months after bariatric surgery, 23% excess weight loss was observed (P < .0001), and diabetes remission was seen in 7 of 10 patients. When compared with preoperative values, after surgery, notable decreases in pancreatic fat volume (P < .01), fatty acid uptake, and blood flow (both P < .05) were seen, whereas no change was seen in pancreatic fat-free volume. The decrease in pancreatic fat volume and the preservation of blood flow were associated with favorable glucose homeostasis and β-cell function. Conclusions: Bariatric surgery elicits marked alterations in pancreatic lipid metabolism and blood flow, which may contribute to the observed improvement in glucose homeostasis and remission of type 2 diabetes.