title: Calorie restriction is a major determinant of the short-term metabolic effects of gastric bypass surgery in obese type 2 diabetic patients.
abstract: OBJECTIVE
  Roux-en-Y gastric bypass (RYGB) and restrictive weight loss interventions, such as gastric banding (GB) and very-low-calorie diets (VLCD) directly impact glucose metabolism, possibly by calorie restriction and/or altered secretion of gut hormones. We aimed to establish the direct endocrine and metabolic effects of RYGB compared to restrictive interventions in obese glucose-tolerant (NGT) subjects and subjects with type 2 diabetes (T2DM).
  
  
  METHODS
  Controlled, nonrandomized observational trial.
  
  
  METHODS
  Four groups of obese females received a mixed meal at baseline and 3 weeks after intervention; NGT-GB (n = 11), NGT-RYGB (n = 16), T2DM-RYGB (n = 15) and T2DM-VLCD (n = 12). Normal weight controls (n = 12) were studied once.
  
  
  RESULTS
  At baseline, all obese subjects were hyperinsulinemic. T2DM was associated with hyperglycaemia and decreased GLP-1 levels. RYGB and VLCD reduced glucose levels to a similar extent in T2DM, insulin levels decreased only after VLCD. Comparison of restrictive intervention vs RYGB showed a more pronounced decrease in glucose and insulin AUC after restriction. In NGT and T2DM subjects, RYGB increased GLP-1 and PYY levels and decreased ghrelin levels, whereas VLCD and GB only increased GIP levels.
  
  
  CONCLUSIONS
  These data indicate that deterioration of glucose metabolism in T2DM is associated with a decline of GLP-1 levels. Calorie restriction facilitates glucose metabolism and blunts hyperinsulinemia in obese (diabetic) humans. Additional duodenal exclusion through RYGB induces gut hormone release and hyperinsulinemia but does not improve postprandial glucose levels any further. Our data thus strongly suggest that calorie restriction underlies the short-term metabolic benefits of RYGB in obese T2DM patients.
authors.affiliation: Department of Endocrinology and Metabolism, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Mirjam A
authors.initials: MA
authors.lastname: Lips
authors.forename: Gerrit H
authors.initials: GH
authors.lastname: de Groot
authors.forename: Jan B
authors.initials: JB
authors.lastname: van Klinken
authors.forename: Edo
authors.initials: E
authors.lastname: Aarts
authors.forename: Frits J
authors.initials: FJ
authors.lastname: Berends
authors.forename: Ignace M
authors.initials: IM
authors.lastname: Janssen
authors.forename: Bert
authors.initials: B
authors.lastname: Van Ramshorst
authors.forename: Bart A
authors.initials: BA
authors.lastname: Van Wagensveld
authors.forename: Dingeman J
authors.initials: DJ
authors.lastname: Swank
authors.forename: Francois
authors.initials: F
authors.lastname: Van Dielen
authors.forename: Ko
authors.initials: K
authors.lastname: Willems van Dijk
authors.forename: Hanno
authors.initials: H
authors.lastname: Pijl
mesh_terms: D050154:Adiposity; D019540:Area Under Curve; D001786:Blood Glucose / Q000032:analysis; D031204:Caloric Restriction; D048909:Diabetes Complications / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D005260:Female; D015390:Gastric Bypass / Q000379:methods*; D054439:Ghrelin / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006728:Hormones / Q000378:metabolism; D006801:Humans; D006943:Hyperglycemia / Q000097:blood; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D007413:Intestinal Mucosa / Q000378:metabolism; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000150:complications / Q000601:surgery*; D015431:Weight Loss
chemical_list: D001786:Blood Glucose; D054439:Ghrelin; D006728:Hormones; D007328:Insulin; D005947:Glucose