title: Surgical removal of omental fat does not improve insulin sensitivity and cardiovascular risk factors in obese adults.
abstract: OBJECTIVE
  Visceral adipose tissue (VAT) is an important risk factor for the metabolic complications associated with obesity. Therefore, a reduction in VAT is considered an important target of obesity therapy. We evaluated whether reducing VAT mass by surgical removal of the omentum improves insulin sensitivity and metabolic function in obese patients.
  
  
  METHODS
  We conducted a 12-month randomized controlled trial to determine whether reducing VAT by omentectomy in 22 obese subjects increased their improvement following Roux-en-Y gastric bypass (RYGB) surgery in hepatic and skeletal muscle sensitivity to insulin study 1. Improvement was assessed by using the hyperinsulinemic-euglycemic clamp technique. We also performed a 3-month, longitudinal, single-arm study to determine whether laparoscopic omentectomy alone, in 7 obese subjects with type 2 diabetes mellitus (T2DM), improved insulin sensitivity study 2. Improvement was assessed by using the Frequently Sampled Intravenous Glucose Tolerance Test.
  
  
  RESULTS
  The greater omentum, which weighed 0.82 kg (95% confidence interval: 0.67-0.97), was removed from subjects who had omentectomy in both studies. In study 1, there was an approximate 2-fold increase in muscle insulin sensitivity (relative increase in glucose disposal during insulin infusion) and a 4-fold increase in hepatic insulin sensitivity 12 months after RYGB alone and RYGB plus omentectomy, compared with baseline values (P<.001). There were no significant differences between groups (P>.87) or group x time interactions (P>.36). In study 2, surgery had no effect on insulin sensitivity (P=.844) or use of diabetes medications.
  
  
  CONCLUSIONS
  These results demonstrate that decreasing VAT through omentectomy, alone or in combination with RYGB surgery, does not improve metabolic function in obese patients.
authors.affiliation: Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St Louis, Missouri, USA.
authors.forename: Elisa
authors.initials: E
authors.lastname: Fabbrini
authors.forename: Robyn A
authors.initials: RA
authors.lastname: Tamboli
authors.forename: Faidon
authors.initials: F
authors.lastname: Magkos
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Marks-Shulman
authors.forename: Aaron W
authors.initials: AW
authors.lastname: Eckhauser
authors.forename: William O
authors.initials: WO
authors.lastname: Richards
authors.forename: Samuel
authors.initials: S
authors.lastname: Klein
authors.forename: Naji N
authors.initials: NN
authors.lastname: Abumrad
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000097:blood / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D015390:Gastric Bypass; D015309:Glucose Clamp Technique; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D050152:Intra-Abdominal Fat / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery*; D010535:Laparoscopy; D015187:Lipectomy / Q000379:methods*; D008099:Liver / Q000378:metabolism / Q000503:physiopathology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism / Q000503:physiopathology; D009765:Obesity / Q000097:blood / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D009852:Omentum / Q000601:surgery*; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D001786:Blood Glucose; D007328:Insulin
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