Obesity and its related metabolic disorders are increasingly a heavy health burden to many parts of the world. Weight control is a well-known important step in avoiding type 2 diabetes mellitus (T2DM). It is also an essential component for normalizing the blood glucose and preventing macrovascular and microvascular insults to patients with diagnosed T2DM. However, life-style modification, physical exercise and dietary adjustment are ineffective measures which are unlikely to confer adequate and sustainable weight loss for the truly obese. On the other hand, large scale long-term follow-up studies have confirmed the role of bariatric surgery in providing durable weight loss and remarkable improvement on medical comorbidities. Among all the bariatric operations, laparoscopic sleeve gastrectomy (LSG) is currently the most widely adopted procedure worldwide because of its simplicity and effectiveness in weight reduction. However, LSG is not without risk. Staple-line hemorrhage, leakage and stenosis are potentially life-threatening complications. LSG is also costly because of the need for expensive laparoscopic staplers.

A new endoscopic bariatric therapy, namely endoscopic sleeve gastroplasty (ESG), has recently been proposed as a non-surgical procedure for the management of obesity with or without diabetes mellitus. Preliminary data based on single arm series or phase II studies have reported promising short and intermediate term weight control effect.

However, whether ESG is a feasible option comparable to LSG in the intermediate term remains an unanswered question. In addition, physical and functional outcomes after ESG were not well documented in most of the reported series.

Realizing there is a knowledge gap in applying ESG to patients with morbid obesity, we propose to study and compare the efficacy of weight control and functional outcomes of ESG against conventional LSG. Through this prospective randomized trial, the safety profiles, quality of life and changes in fasting and post-prandial gut hormone secretion after the two procedures will also be assessed and compared. The evidence thus generated shall lay a scientific foundation for ESG which may become an alternative choice for patients who have concerns about complication and irreversibility of most bariatric surgery.

Inclusion Criteria:

1. A BMI > 35 kg/m2
2. A BMI > 30 kg/m2 with T2DM
3. A BMI>3 30kg/m2 with 2 or more co-morbidities

Exclusion Criteria:

1. Significant anaesthetic risk (> ASA III)
2. History of diabetic ketoacidosis or hyperosmolar coma
3. Uncontrolled T2 DM with HbA1c > 12%
4. A BMI > 45 kg/m2
5. Malignancy diagnosed within 5 years
6. Endoscopic findings of any pre-neoplastic/neoplastic lesions, portal hypertensive gastropathy or significant varices
7. Chronic renal failure requiring dialysis
8. Previous upper abdominal surgery (including bariatric surgery) affecting gastroduodenal configuration
9. Major psychiatric illness including major depression and substance abuse
10. Pregnancy or ongoing breast-feeding
11. Inmates