Silastic Ring Gastric Bypass Versus Sleeve Gastrectomy for Type 2 Diabetes Mellitus in Obese Patients
Condition: Type 2 Diabetes Mellitus; Obesity
MeSH terms: Diabetes Mellitus; Diabetes Mellitus, Type 2
Study type: Interventional

Summary: 
      Type 2 diabetes (T2DM) and obesity are becoming increasingly common in New Zealand (NZ) and
      worldwide. Both are associated with a risk of early mortality (death). Whilst weight loss
      surgery is known to be effective for weight loss, current research suggests that it may also
      be effective in resolving T2DM in around 60-80% of patients, with some no longer requiring
      their medication. The mechanism for this remains unclear.

      Two main types of weight loss surgery are performed in NZ public hospitals, which include
      gastric bypass and sleeve gastrectomy. The gastric bypass is a more complex procedure
      compared to the sleeve gastrectomy. Whilst both appear to be effective for weight loss (with
      most patients losing more than 60% of their excess weight), it is still not known which one
      is better for treating T2DM.

      This study will therefore compare which of these two surgical procedures is most effective at
      treating T2DM in obese patients, as well as comparing whether there are any differences in
      the amount of weight lost, side effects and quality of life.
    

Detailed description: 
      EFFECTS OF DIABETES AND OBESITY The World Health Organization indicates that 346 million
      people worldwide have diabetes. This is expected to double between 2005 and 2030. Type 2
      diabetes mellitus (T2DM) accounts for 90% of people with diabetes and is known to result from
      a combination of physical inactivity and excess weight. In New Zealand (NZ) more than 200,000
      people have diabetes, with an incidence amongst the Maori and Pacific population three times
      greater than other NZ ethnic groups. Obesity is also more prevalent amongst this population,
      with each 5 kg/m2 higher BMI resulting in a 30% higher overall mortality.

      Over the last 10 years bariatric surgery has been recognised as an effective strategy to
      treat both morbid obesity and T2DM. Indeed in a systematic review in 2004, by Buchwald et al,
      an overall T2DM remission rate of 76% was seen following bariatric surgery. In March 2011 the
      International Diabetic Federation released a position statement recognising bariatric surgery
      as an appropriate treatment option in those patients with T2DM and a body mass index (BMI)>
      OR = 35kg/m2 or BMI 30-35kg/m2 where medical treatment has failed.

      SURGICAL PROCEDURES Laparoscopic Roux-en-Y gastric bypass (LRYGB): Currently the most
      commonly performed bariatric procedure worldwide. It combines a restrictive and malabsorptive
      (duodenal bypass) component, with a mean excess weight loss (EWL) of 61.6% and T2DM remission
      rate of 83.8% reported. Analysis of our own series identified a T2DM remission rate at 1 year
      of 88%.

      Laparoscopic sleeve gastrectomy (LSG): A predominantly restrictive procedure (no bypass
      component), which was initially used as a staged approach to biliopancreatic diversion and
      duodenal switch (BPD-DS), has gained increasing popularity due its relatively lower technical
      complexity. In a recent systematic review a mean EWL of >45% (range 6.3 - 74.6%) was reported
      with an overall T2DM remission rate of 66%, which reduced to 59% where only those studies
      reporting 1 year outcomes were analysed. There is however a lack of medium and long term data
      and meta-analysis is currently not feasible in view of the high heterogeneity of studies and
      the lack of randomised controlled trials.

      MECHANISM OF ACTION The mechanism of T2DM remission following these procedures remains
      unclear and may relate to the effects of reduced caloric intake or gut hormone effects in the
      proximal and distal intestine. Following LRYGB, the improvement in glycaemic control appears
      to occur before weight loss and may be explained by exclusion of the duodenum / proximal
      jejunum reducing insulin resistance or an enhanced hormonal response resulting from nutrients
      in the distal small bowel. Following LSG both hormonal changes and a hindgut theory have been
      proposed. In addition there is increasing evidence that changes in bone mineral density and
      body composition, with a reduction in body fat and lean tissue mass, and an increase in
      resting energy expenditure, may also occur following gastric bypass and other restrictive
      surgical procedures. It is unclear whether such changes correlate with the degree of
      comorbidity resolution after surgery.

      CONCLUSION At the current time much of the data relating to LSG is based on non-randomised
      observational studies and it remains unclear whether the promising T2DM remission rates and
      excess weight loss reported will be sustainable in the long term. In the only published
      randomised trial, by Lee et al. from Taiwan, to compare T2DM remission rates at 1 year
      between LSG and gastric bypass in BMI < 35, a much higher remission rate of 93% was seen
      following gastric bypass compared with 47% following LSG. Given the potential technical
      benefits of LSG, there is an urgent need to compare the efficacy of this procedure with the
      more commonly performed LRYGB procedure, at a time when clinical equipoise remains, in order
      to determine the optimum approach to T2DM in the future.
    

Intervention name(s): Laparoscopic Silastic Ring Roux-en-Y Gastric Bypass; Laparoscopic Sleeve gastrectomy
Intervention type(s): Procedure; Procedure
Intervention description(s): An isolated lesser curve-based gastric pouch will be created, with an antecolic antegastric Roux limb fashioned measuring 100 cm in length. The biliopancreatic limb will measure 50cm for all patients. A 6.5cm silastic ring will be placed above the gastrojejunostomy to prevent long term stomal dilatation.; Resection of the greater curvature of the stomach from the distal antrum (2cm proximal to pylorus) to the angle of His, using a laparoscopic stapling device over a 36Fr bougie, will be performed to create a lesser curve gastric sleeve
Other intervention name(s): Silastic ring Gastric bypass; Fobi pouch; RYGB; LRYGBP; LRYGB; GBP; SR gastric bypass; Vertical sleeve gastrectomy
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Gastric bypass; Silastic ring gastric bypass; Roux-en-Y gastric bypass; Sleeve gastrectomy; Body composition analysis