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

Abstract

ObjectiveThe objective of this study was to quantify hormones that regulate energy and glucose homeostasis in order to establish possible mechanisms for the greater efficacy of Roux-en-Y gastric bypass (RYGB) compared with laparascopic adjustable gastric banding (LAGB) in achieving weight loss and improved insulin sensitivity.DesignLongitudinal study of patients undergoing LAGB (n=15) and RYGB (n=28) who were studied prior to surgery and at 2, 12, 26 and 52 wks afterwards.MeasurementsFasting blood samples were drawn at each visit. Postprandial blood samples were also obtained prior to surgery and at 26 and 52 wks. Samples were assayed for peptide YY (PYY), ghrelin, glucagon-like peptide-1 (GLP-1), glucose, insulin, leptin, thyrotropic hormone (TSH), free T4 and free T3.ResultsAt one 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/m2). At wk 52, area under the curve (AUC) for PYY in RYGB subjects was greater than LAGB (P<0.01). GLP-1 levels at 30 min post-meal were three-fold greater after RYGB compared with LAGB (P<0.001). Conversely, ghrelin AUC increased after LAGB at wk 52 (P<0.05) but tended to decrease after RYGB. Fasting glucose, insulin, and leptin, and HOMA-IR decreased in both groups over time but were significantly lower at wk 52 after RYGB compared with LAGB. The change in leptin correlated significantly with weight loss in LAGB (r=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 (P<0.01) after RYGB.ConclusionsDifferences in levels of gut hormones may play a role in promoting greater weight loss and insulin sensitivity after RYGB compared with LAGB, however, weight loss may be limited by decreases in free T3 and leptin.

Comparison of laparoscopic Roux-en-Y gastric bypass with laparoscopic sleeve gastrectomy for morbid obesity or type 2 diabetes mellitus: a meta-analysis of randomized controlled trials

“…25,26 The difference in insulin resistance in the postoperative period between the 2 procedures found in this meta-analysis also supports the theory that duodenum exclusion is helpful for the reduction of insulin resistance. In recent studies, Korner and colleagues 27 found that reduction of insulin resistance correlated significantly with weight loss only in patients who underwnt gastric banding, not in those who had gastric bypass, and Bikman and colleagues 28 found that improved insulin sensitivity after gastric bypass was due to something other than weight loss. Because the duodenum was recently found to have a novel intestine-brain-liver neurocircuit to increase hepatic insulin sensitivity, it is possible that gastrointestinal surgery may help mediate antidiabetes effects, although this is currently unclear.…”

Roux-en-Y gastric bypass: effects on feeding behavior and underlying mechanisms

“…Thus, dieting-induced weight loss is accompanied by an active "defense" of the higher body weight (34). Notably, in the case of RYGBP, the sustained body weight reduction occurs despite dramatic falls in circulating leptin levels (35). However, RYGBP-induced gut hormonal changes contrast strongly with those seen after dieting, as the former result in reduced hunger and more satiety, which lead to sustained weight loss (36).…”

Effects of leptin replacement alone and with exendin-4 on food intake and weight regain in weight-reduced diet-induced obese rats

“…Of these substances, only a single dosing regimen of a single substance (exendin-4) was able to produce a sustained ϳ15-30% reduction in daily food intake and weight loss for Ͼ2 wk (31). However, exendin-4's effect waned after 17 days, and coadministration of PYY and exendin-4 at various dosing combinations did not produce a more prolonged effect than the GLP-1 receptor agonist exendin-4 alone despite recent studies suggesting that chronic elevation in gut hormones PYY and GLP-1 may cause the significant weight loss that occurs with Roux-en-Y gastric bypass surgery (19,20).…”