The effects of bariatric surgery on pancreatic lipid metabolism and blood flow.

Abstract

Bariatric surgery leads to a rapid and sustained weight loss often accompanied with improvement in glucose homeostasis. The objective of this study was to investigate the effects of bariatric surgery on pancreatic lipid metabolism, blood flow, and glycemic control. This was a longitudinal study. The study was conducted in a clinical research center. This study included 27 morbidly obese and 15 healthy control subjects. Measurements were performed using positron emission tomography with the palmitate analog 14(R,S)-[(18)F]fluoro-6-thia-heptadecanoic acid and radiowater ([(15)O]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). 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. 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. 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.