Acute effects of gastric bypass versus gastric restrictive surgery on beta-cell function and insulinotropic hormones in severely obese patients with type 2 diabetes

Int J Obes (Lond). 2010 Mar;34(3):462-71. doi: 10.1038/ijo.2009.254. Epub 2009 Dec 22.


Context: Hyperglycemia resolves quickly after bariatric surgery, but the underlying mechanism and the most effective type of surgery remains unclear.

Objective: To examine glucose metabolism and beta-cell function in patients with type 2 diabetes mellitus (T2DM) after two types of bariatric intervention; Roux-en-Y gastric bypass (RYGB) and gastric restrictive (GR) surgery.

Design: Prospective, nonrandomized, repeated-measures, 4-week, longitudinal clinical trial.

Patients: In all, 16 T2DM patients (9 males and 7 females, 52+/-14 years, 47+/-9 kg m(-2), HbA1c 7.2+/-1.1%) undergoing either RYGB (N=9) or GR (N=7) surgery.

Outcome measures: Glucose, insulin secretion, insulin sensitivity at baseline, and 1 and 4 weeks post-surgery, using hyperglycemic clamps and C-peptide modeling kinetics; glucose, insulin secretion and gut-peptide responses to mixed meal tolerance test (MMTT) at baseline and 4 weeks post-surgery.

Results: At 1 week post-surgery, both groups experienced a similar weight loss and reduction in fasting glucose (P<0.01). However, insulin sensitivity increased only after RYGB, (P<0.05). At 4 weeks post-surgery, weight loss remained similar for both groups, but fasting glucose was normalized only after RYGB (95+/-3 mg 100 ml(-1)). Insulin sensitivity improved after RYGB (P<0.01) and did not change with GR, whereas the disposition index remained unchanged after RYGB and increased 30% after GR (P=0.10). The MMTT elicited a robust increase in insulin secretion, glucagon-like peptide-1 (GLP-1) levels and beta-cell sensitivity to glucose only after RYGB (P<0.05).

Conclusion: RYGB provides a more rapid improvement in glucose regulation compared with GR. This improvement is accompanied by enhanced insulin sensitivity and beta-cell responsiveness to glucose, in part because of an incretin effect.

Publication types

  • Clinical Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Bariatric Surgery / methods*
  • Blood Glucose / metabolism*
  • Body Mass Index
  • Body Weight
  • Diabetes Mellitus, Type 2 / metabolism*
  • Diabetes Mellitus, Type 2 / surgery
  • Female
  • Gastric Bypass / methods
  • Gastrointestinal Hormones / metabolism
  • Glucagon-Like Peptide 1 / metabolism*
  • Humans
  • Insulin / blood
  • Insulin Resistance
  • Insulin-Secreting Cells / metabolism*
  • Male
  • Middle Aged
  • Obesity, Morbid / metabolism
  • Obesity, Morbid / surgery*
  • Prospective Studies
  • Weight Loss


  • Blood Glucose
  • Gastrointestinal Hormones
  • Insulin
  • Glucagon-Like Peptide 1