title: Differential effect of weight loss on insulin resistance in surgically treated obese patients.
abstract: OBJECTIVE
  To compare the effects of equivalent weight loss induced by two bariatric surgical techniques on insulin action in severely obese patients.
  
  
  METHODS
  Eighteen nondiabetic patients with severe obesity (mean [+/- SD] body mass index: 53.5 +/- 9.0 kg/m(2)) and 20 sex- and age-matched lean subjects (body mass index: 23.8 +/- 3.0 kg/m(2)) underwent metabolic studies, including measurement of insulin sensitivity by the insulin clamp technique. Patients then underwent either vertical banded gastroplasty with Roux-en-Y gastric bypass, or biliopancreatic diversion, and were restudied at 5 to 6 months and again at 16 to 24 months postsurgery.
  
  
  RESULTS
  At baseline, patients were hyperinsulinemic (194 +/- 47 pmol/L vs. 55 +/- 25 pmol/L, P < 0.0001), hypertriglyceridemic (1.56 +/- 0.30 mmol/L vs. 0.78 +/- 0.32 mmol/L, P < 0.0001), and profoundly insulin resistant (insulin-mediated glucose disposal: 20.8 +/- 4.4 micromol/min/kg fat-free mass vs. 52.0 +/- 10.1 micromol/min/kg, P < 0.0001) as compared with controls. Weight loss by the two procedures was equivalent in both amount (averaging -53 kg) and time course. In the gastric bypass group, insulin sensitivity improved (23.8 +/- 6.0 micromol/min/kg at 5 months and 33.7 +/- 11.3 micromol/min/kg at 16 months, P < 0.01 vs. baseline and controls). In contrast, in the biliopancreatic diversion group, insulin sensitivity was normalized already at 6 months (52.5 +/- 12.4 micromol/min/kg, P = 0.72 vs. controls) and increased further at 24 months (68.7 +/- 9.5 micromol/min/kg, P < 0.01 vs. controls) despite a persistent obese phenotype (body mass index: 33.2 +/- 8.0 kg/m(2)).
  
  
  CONCLUSIONS
  In surgically treated obese patients, insulin sensitivity improves in proportion to weight loss with use of predominantly restrictive procedures (gastric bypass), but is reversed completely by predominantly malabsorptive approaches (biliopancreatic diversion) long before normalization of body weight. Selective nutrient absorption and gut hormones may interact with one another in the genesis of the metabolic abnormalities of obesity.
authors.affiliation: Department of Medicine, State University of Campinas, São Paulo, Brazil.
authors.forename: Elza
authors.initials: E
authors.lastname: Muscelli
authors.forename: Gertrude
authors.initials: G
authors.lastname: Mingrone
authors.forename: Stefania
authors.initials: S
authors.lastname: Camastra
authors.forename: Melania
authors.initials: M
authors.lastname: Manco
authors.forename: Juliano Alves
authors.initials: JA
authors.lastname: Pereira
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Pareja
authors.forename: Ele
authors.initials: E
authors.lastname: Ferrannini
mesh_terms: D000328:Adult; D000713:Anastomosis, Roux-en-Y; D015904:Biliopancreatic Diversion; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D016022:Case-Control Studies; D005260:Female; D015390:Gastric Bypass; D015391:Gastroplasty / Q000379:methods*; D015309:Glucose Clamp Technique; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D009767:Obesity, Morbid / Q000097:blood / Q000601:surgery*; D013997:Time Factors; D014280:Triglycerides / Q000097:blood; D015431:Weight Loss
chemical_list: D001786:Blood Glucose; D007328:Insulin; D014280:Triglycerides