title: Changes in post-prandial glucose and pancreatic hormones, and steady-state insulin and free fatty acids after gastric bypass surgery.
abstract: BACKGROUND
  Changes in the multiple mechanisms that regulate glucose metabolism after gastric bypass (RYGB) are still being unveiled. The objective of this study was to compare the changes of glucose and pancreatic hormones [C-peptide, glucagon, and pancreatic polypeptide (PP)] during a meal tolerance test (MTT) and steady-state insulin and free fatty acid (FFA) concentrations during euglycemic-hyperinsulinemic clamp 14 days and 6 months after RYGB in morbidly obese nondiabetic patients.
  
  
  METHODS
  Two groups were studied at baseline and at 14 days: the RYGB followed by caloric restriction group (RYGB, n = 12) and the equivalent caloric restriction alone group (Diet, n = 10), to control for energy intake and weight loss. The RYGB group was studied again at 6 months to assess the changes after substantial weight loss. During MTT, the early and overall changes in glucose and pancreatic hormone concentrations were determined, and during the clamp, steady-state insulin and FFA concentrations were assessed.
  
  
  RESULTS
  After 14 days, RYGB patients had enhanced postprandial glucose, C-peptide, and glucagon responses, and decreased postprandial PP concentrations. Steady-state insulin concentrations were decreased at 14 days only in RYGB patients, and FFA increased in both groups. Six months after RYGB and substantial weight loss, the decrease in insulin concentrations during clamp persisted, and there were further changes in postprandial glucose and glucagon responses. FFA concentrations during clamp were significantly lower at 6 months, relative to presurgical values.
  
  
  CONCLUSIONS
  In morbidly obese nondiabetic patients, RYGB produces early changes in postmeal glucose, C-peptide, glucagon, and PP responses, and it appears to enhance insulin clearance early after RYGB and improve insulin sensitivity in adipose tissue at 6 months postsurgery. The early changes cannot be explained by caloric restriction alone.
authors.affiliation: Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; Department of Surgery, University of California San Francisco, San Francisco, California. Electronic address: campos@surgery.wisc.edu.
authors.forename: Guilherme M
authors.initials: GM
authors.lastname: Campos
authors.affiliation: Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; Department of Surgery, University of California San Francisco, San Francisco, California; Department of Surgery, Paracelsus Medical University, Salzburg, Austria.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Rabl
authors.affiliation: Department of Molecular Biosciences, School of Veterinary Medicine and Department of Nutrition, University of California Davis, Davis, California.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Havel
authors.affiliation: Department of Medicine, University of California San Francisco, San Francisco, California.
authors.forename: Madhu
authors.initials: M
authors.lastname: Rao
authors.affiliation: Touro University-California, Vallejo, California.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Schwarz
authors.affiliation: Department of Medicine, University of California San Francisco, San Francisco, California.
authors.forename: Morris
authors.initials: M
authors.lastname: Schambelan
authors.affiliation: Department of Medicine, University of California San Francisco, San Francisco, California.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Mulligan
mesh_terms: D001786:Blood Glucose / Q000378:metabolism*; D031204:Caloric Restriction; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005260:Female; D005500:Follow-Up Studies; D015390:Gastric Bypass; D015309:Glucose Clamp Technique; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000178:diet therapy / Q000378:metabolism* / Q000601:surgery; D010187:Pancreatic Hormones / Q000378:metabolism*; D011182:Postoperative Care; D019518:Postprandial Period / Q000502:physiology; D015431:Weight Loss / Q000502:physiology
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D010187:Pancreatic Hormones
keywords: Bariatric surgery; C-peptide; Free fatty acids; Gastric bypass; Glucagon; Glucose; Gut hormones; Hyperinsulinemic euglycemic clamp; Incretins; Insulin clearance; Insulin resistance; Type 2 diabetes