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As the prevalence of obesity rises, obesity related co-morbidities are expected to rise, in particular T2DM. Surgical intervention for obesity, also referred to as bariatric (from the Greek ‘baros’, meaning ‘weight’) surgery, effects weight loss by modifying gastro-intestinal anatomy. It is becoming increasingly recognised that surgery for weight loss such as Roux-En-Y Gastric Bypass (RYGB) can substantially reduce T2DM rates. Hence, the term “Metabolic and Bariatric Surgery” (MBS). The Swedish Obesity Study showed a significant reduction in mortality, coronary events, T2DM and even cancer rates after bariatric surgery over a 15-year follow-up.
The Obesity Clinical Practice Guidelines published by the Ministry of Health, Singapore in 2004, endorses the role of surgery once patients fulfill specific criteria related to weight and co-morbid conditions. Surgery is medically indicated if a patient’s body mass index (BMI) is higher than 37.5 kg/m2 without any comorbidities (Class III obesity) or above 32.5 kg/m2 (Class II obesity) with co-morbidities such as diabetes, hypertensions, hyperlipidaemia, obstructive sleep apnoea (OSA), etc. The American Diabetes Association in its most recent 2009 guidelines, recommended the use of MBS as one of the modalities to treat T2DM in obese patients (“diabesity”).
In Singapore, we are seeing increasing numbers of relatively young patients in their 20s -40s with hyperlipidaemia, hypertension and T2DM, who are obese. Weight loss, when achieved earlier in the course of these metabolic disorders, is more likely to ameliorate or even reverse these diseases. A number of cost analyses performed in the USA, Canada, Great Britain and Australia have shown that surgery is not only cost-effective, it may even represent a cost-saving to the health care provider in the long term.
Management of the obese patient requires a multi-disciplinary team consisting of specialists in endocrinology/obesity, exercise, nutrition and surgery. The decision to proceed to surgery must not be taken lightly and the intervention is merely one step in the overall continuum of care. Surgical options range from the temporary, endoscopic placement of a gastric balloon, to restrictive and malabsorptive procedures.
Endoscopic Treatment
Gastric Balloon
In this procedure, a silicone balloon is placed in the stomach by endoscopy and filled with a saline solution to give patients a sense of fullness, thereby reducing their food intake. Although it is an effective method of weight loss, the balloon must be removed after 6 months because of degradation by gastric acid.
 Restrictive surgical procedures
Laparoscopic adjustable gastric banding (LAGB) (Figure 1a)
LAGB is a restrictive procedure used as a solution for morbid obesity. An adjustable silicone band is placed around the upper part of the stomach to reduce the size of the stomach so that a person feels full faster, thus eating less and ultimately losing weight.
The pouch and the outlet should be small enough to restrict intake adequately yet not too small to cause obstruction. The band is deemed adjustable because a subcutaneous port implanted under the skin allows for fine adjustment of the outlet diameter.
 Laparoscopic sleeve gastrectomy (LSG) (Figure 1b)
This is a restrictive procedure where the stomach is tubularised and the excess part is removed. About 80% of the stomach can be removed in this way. Although this is a relatively new procedure, early results show that weight loss after LSG is comparable to LAGB. Unlike the LAGB, this procedure is performed once only and no adjustments are required thereafter.
 Restrictive and Malabsorptive Procedures
Laparoscopic Roux-en-Y gastric bypass (LRYGB) (Figure 1c)
This is the most complex bariatric surgery available at Singapore General Hospital. Utilising 5 trocars ranging from 5 to 12mm, a small gastric pouch is first created and then a bypass to the small intestine (jejunum) is performed. LRYGB effects weight loss in 2 ways. It reduces caloric intake and shunts food into the mid-jejunum, thus altering the mechanism of digestion. Evidence from large cohort studies and meta-analyses show that bypass procedures have a profound effect on gastro-intestinal physiology and are remarkably effective in correcting metabolic disorders such T2DM and hyperlipidaemia.
Figure 1. Adapted from DeMaria EJ. Bariatric surgery for morbid obesity. N Engl J Med. 2007;356:2176-2183.
Preoperative preparation
As there are risks involved, patients will be thoroughly assessed first to determine their suitability for bariatric surgery. Pre-operative endoscopic, psychological, respiratory and cardiac evaluation may be necessary. A special low calorie diet and vitamins are commenced 2 weeks before surgery to improve patients’ surgical fitness. Breathing and physical exercises are also better started pre-operatively.
Surgical technique
 All procedures are performed using minimally invasive (MIS) techniques. (Figure 2a) Endoscopic gastric balloon placement can be done as a day case procedure, while after laparoscopic surgery patients can expect to stay in hospital for about 3 days. Less than 1% mortality and about 10% morbidity rates are quoted for these procedures. The major complications are venous thrombo-embolism and intestinal leaks leading to sepsis. Before discharge from hospital, an upper gastro-intestinal contrast study may be performed to confirm that it is safe to resume oral intake. (Figure 2b)
Post-surgery – starting a new life!
Surgery helps patients learn a completely new lifestyle. Food intake may be limited to fluids for the first 2 weeks. After this period, soft food and then solids can be gradually re-introduced under guidance. In addition to superior weight loss compared to medical and lifestyle intervention alone, bariatric surgery can also improve co-morbidities such as type II diabetes mellitus, hyperlipidaemia, hypertension and obstructive sleep apnoea (OSA).
After restrictive procedures, patients can expect to lose about 10-30% of their body weight, whereas after LRYGB, weight loss is about 20-40%. The rate of reversal of T2DM after RYGB is dependent on the duration of the disease; patients suffering from T2DM for less than 5 years can expect an 80% chance of remission, whereas only 50% of those having T2DM for more than 5 years manage to come off their medication.
In order to achieve the best results, patients will continue to be monitored for life by a multidisciplinary team comprising of a surgeon, physician, physiotherapist and dietitian. Studies have shown that a better relationship between patients and their managing team can lead to better outcomes in terms of weight loss and resolution of co-morbidities.
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