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


METHODS
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.


METHODS
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 T(4) and free T(3).


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 (P<0.01). GLP-1 levels at 30 min after meal were threefold greater after RYGB compared with LAGB (P<0.001). Conversely, ghrelin AUC increased after LAGB at week 52 (P<0.05) but tended to decrease after RYGB. Fasting glucose, insulin, and leptin and homeostasis model of assessment (HOMA-IR) decreased in both groups over time but were significantly lower at week 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 T(3) (P<0.01) after RYGB.


CONCLUSIONS
Differences 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 T(3) and leptin.
Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA. jk181@columbia.edu
J
J
Korner
W
W
Inabnet
G
G
Febres
I M
IM
Conwell
D J
DJ
McMahon
R
R
Salas
C
C
Taveras
B
B
Schrope
M
M
Bessler
D001786:Blood Glucose / Q000378:metabolism*; D005260:Female; D015390:Gastric Bypass; D015391:Gastroplasty / Q000379:methods; D052216:Glucagon-Like Peptide 1 / Q000378:metabolism*; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000378:metabolism* / Q000601:surgery; D019518:Postprandial Period; D011446:Prospective Studies; D015431:Weight Loss / Q000502:physiology*
D001786:Blood Glucose; D052216:Glucagon-Like Peptide 1