title: Changes in GIP gene expression following bariatric surgery.
abstract: BACKGROUND
  After bariatric surgery, there is a significant improvement in type 2 diabetes (T2D). T2D has been linked to incretins, including glucose-dependent insulinotropic polypeptide (GIP). Analysis of bariatric surgery patients may help to understand the link between GIP and T2D.
  
  
  METHODS
  Twenty-three morbidly obese patients underwent Roux-en-Y gastric bypass (RYGB) or gastric banding. Overall, there were 12 RYGB (5 T2D; 7 nondiabetic) patients and 11 gastric band (7 T2D; 4 nondiabetic) patients. Preoperative and postoperative blood samples were collected. Total RNA was extracted, cDNA synthesized, and real-time quantitative PCR were used to quantify gene expression. Student's t test was used for statistical analysis.
  
  
  RESULTS
  Postoperatively, T2D resolved or improved in 83.3 % (10/12) of the diabetic patients. Six (4 RYGB, 2 bands) patients discontinued hypoglycemic medications and four (3 RYGB, 1 band) patients discontinued the majority of their hypoglycemic agents. The remaining two diabetic patients (bands) showed no improvement. Postoperative GIP gene expression increased 4.36-fold (p = 0.02) in diabetic RYGB patients, whereas diabetic band patients increased 1.4-fold (p = 0.25). All diabetic patients with either resolution or improvement of T2D, had a 3.4-fold increase (p = 0.01) but nonresponders decreased 0.69-fold (p = 0.41). Nondiabetic RYGB patients increased 2.21-fold (p = 0.07) versus a 0.81-fold (p = 0.37) decrease of nondiabetic band patients.
  
  
  CONCLUSIONS
  This is one of the initial studies that show a significant increase in GIP gene expression following a RYGB. This increase correlates with the clinical resolution of T2D. The anatomical changes after RYGB may account for these changes. Based on this data, GIP may be a key peptide in the "foregut hypothesis" for resolution of T2D.
authors.affiliation: Department of Surgery, The George Washington University Medical Center, 2150 Pennsylvania Avenue NW, Washington, DC 20037, USA. erinmoranatkin@gmail.com
authors.forename: Erin
authors.initials: E
authors.lastname: Moran-Atkin
authors.forename: Fred
authors.initials: F
authors.lastname: Brody
authors.forename: Sidney W
authors.initials: SW
authors.lastname: Fu
authors.forename: Marcos
authors.initials: M
authors.lastname: Rojkind
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000601:surgery; D015390:Gastric Bypass; D005749:Gastric Inhibitory Polypeptide / Q000097:blood / Q000235:genetics*; D015391:Gastroplasty; D015870:Gene Expression; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D009767:Obesity, Morbid / Q000097:blood / Q000601:surgery; D010865:Pilot Projects; D011184:Postoperative Period; D011446:Prospective Studies; D012313:RNA / Q000097:blood; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D005749:Gastric Inhibitory Polypeptide; D006442:Glycated Hemoglobin; D012313:RNA; C517652:hemoglobin A1c protein, human