title: Gastric bypass surgery has a weight-loss independent effect on post-challenge serum glucose levels.
abstract: BACKGROUND
  Gastric bypass surgery seems to have an effect on glucose metabolism beyond what is mediated through weight reduction. The magnitude of this effect on fasting and post-challenge glucose levels remains unknown.
  
  
  RESULTS
  Morbidly obese subjects without known diabetes performed a 75 g oral glucose tolerance test before and after either gastric bypass surgery (n = 64) or an intensive lifestyle intervention programme (n = 55), ClinicalTrials.gov identifier NCT00273104. The age-adjusted effects of the therapeutic procedures and percentage weight change on fasting and 2-h glucose levels at 1 year were explored using multiple linear regression analysis. Mean (SD) serum fasting and 2-h glucose levels at baseline did not differ between the surgery and lifestyle groups. Weight-loss after surgical treatment and lifestyle intervention was 30 (8) and 9 (10) % (p < 0.001). At 1 year, fasting and 2-h glucose levels were significantly lower in the surgery group than in the lifestyle group, 4.7 (0.4) versus 5.4 (0.7) mmol/l and 3.4 (0.8) versus 6.0 (2.4) mmol/l, respectively (both p < 0.001). Gastric bypass and weight-loss had both independent glucose-lowering effects on 2-h glucose levels [B (95 % CI) 1.4 (0.6-2.3) mmol/l and 0.4 (0.1-0.7) mmol/l per 10 % weight-loss, respectively]. Fasting glucose levels were determined by weight change [0.2 (0.1-0.3) mmol/l per 10 % weight-loss] and not by type of treatment.
  
  
  CONCLUSIONS
  Gastric bypass surgery has a clinically relevant glucose-lowering effect on post-challenge glucose levels which is seemingly not mediated through weight-loss alone.
authors: Morbid Obesity Centre, Vestfold Hospital Trust, post box 2168, 3103 Tønsberg, Norway.
authors: Dag
authors: D
authors: Hofsø
authors: Department of Endocrinology, Morbid Obesity and Preventive Medicine, Oslo University Hospital, Oslo, Norway ; Faculty of Medicine, University of Oslo, Oslo, Norway.
authors: Kåre I
authors: KI
authors: Birkeland
authors: Department of Biomedical Sciences, Endocrinology Research Section, Copenhagen, Denmark.
authors: Jens J
authors: JJ
authors: Holst
authors: Faculty of Medicine, University of Oslo, Oslo, Norway ; Section of Endocrinology, Department of Medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway.
authors: Jens
authors: J
authors: Bollerslev
authors: Morbid Obesity Centre, Vestfold Hospital Trust, post box 2168, 3103 Tønsberg, Norway ; Department of Surgery, Vestfold Hospital Trust, Tønsberg, Norway.
authors: Rune
authors: R
authors: Sandbu
authors: Morbid Obesity Centre, Vestfold Hospital Trust, post box 2168, 3103 Tønsberg, Norway ; Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
authors: Jo
authors: J
authors: Røislien
authors: Morbid Obesity Centre, Vestfold Hospital Trust, post box 2168, 3103 Tønsberg, Norway ; Faculty of Medicine, University of Oslo, Oslo, Norway.
authors: Jøran
authors: J
authors: Hjelmesæth
keywords: Gastric bypass surgery; Hypoglycaemia; Morbid obesity