Effect of Bariatric Surgery on Mechanisms of Type 2 Diabetes (Stampede II)

• Test the effect of gastric bypass surgery on glycemic control in obese type 2 DM patients [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  The working hypothesis for this aim is that significantly more obese T2DM patients who undergo RYGB surgery will achieve glycemic control based on a primary endpoint of an HbA1c ≤ 6.5% at 12 months, than patients managed by intensive medical therapy.
  
  

• Determine the effects of gastric bypass surgery on pancreatic beta cell function and incretin hormone secretion in obese type 2 dm patients [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  The working hypothesis for this aim is that a primary physiological link between obesity and T2DM is specific to beta-cell dysfunction; RYGB will reverse beta-cell dysfunction by increasing postprandial incretin secretion.
  
  

Obesity and type 2 diabetes mellitus (T2DM) are two of the greatest public health problems of the 21st century. Lifestyle changes and pharmacotherapy, which are mainstay treatments for T2DM have had limited success. More intensive lifestyle weight management such as in the Look AHEAD trial reported an 8.6% weight loss after 1 year, while the Diabetes Prevention Program reported a 7% weight loss after 2 years, and a 58% decrease in the risk of developing T2DM. In contrast,we have observed a 31% weight loss together with 83% remission of T2DM in severely obese patients after Roux-en-Y gastric bypass (RYGB) surgery. However, direct evidence of the glycemic benefits of bariatric surgery from randomized control trials is lacking; there is no clear consensus that RYGB surgery is a good treatment option for moderately obese T2DM patients; and the mechanisms responsible for reversing T2DM after surgery remain unclear but may involve pancreatic insulin secretion and skeletal muscle and hepatic insulin resistance.

The objective of this application is to evaluate the effects of RYGB surgery on glycemic control and underlying mechanisms that contribute to T2DM in obese subjects (BMI: 30-40 kg/m2). Our central hypothesis is that RYGB surgery will reduce hyperglycemia via reversal of beta-cell dysfunction and decrease hepatic and peripheral insulin resistance. The approach requires a 12-month randomized controlled trial. The rationale is based on data showing that RYGB lowers fasting and postprandial glucose, and increases the GLP-1 response to a meal. However, the therapeutic efficacy of RYGB surgery in obesity-related T2DM needs to be demonstrated in a randomized trial.