Prospective study of gut hormone and metabolic changes after adjustable gastric banding and Roux-en-Y gastric bypass

Abstract

Objective: The objective of this study was to quantify hormones that regulate energy and glucose homeostasis to establish possible mechanisms for the greater efficacy of Roux-en-Y gastric bypass (RYGB) compared with laparoscopic adjustable gastric banding (LAGB) in achieving weight loss and improved insulin sensitivity. Design: Longitudinal study of patients undergoing LAGB (n=15) and RYGB (n=28) who were studied before surgery and at 2, 12, 26 and 52 weeks afterwards. Measurements: Fasting blood samples were drawn at each visit. Postprandial blood samples were also obtained before surgery and at 26 and 52 weeks. Samples were assayed for peptide YY (PYY), ghrelin, glucagon-like peptide-1 (GLP-1), glucose, insulin, leptin, thyrotropic hormone, free T₄ and free T₃. Results: At 1 year there was greater weight loss in RYGB compared with LAGB patients (30 vs 15%), but final body mass index was similar (34 vs 33 kg m⁻²). At week 52, area under the curve (AUC) for PYY in RYGB subjects was greater than LAGB (PPPr=0.86) and RYGB (r=0.77), however, HOMA-IR correlated significantly with weight loss only in LAGB (r=0.78), and not RYGB (r=0.15). There was a significant decrease in free T₃ (P3 and leptin.