Obesity is a growing problem worldwide that is closely related to type 2 diabetes mellitus (T2DM). The Roux-en-Y gastric bypass (RYGBP), a restrictive and malabsorptive bariatric procedure, shows mounting evidence of inducing improvement of T2DM. Few studies, especially those examining the early changes in diabetic parameters, have been done in the Asian population. All morbidly obese patients with T2DM undergoing RYGBP at our institution from August 2008 to January 2010 were prospectively studied. Six patients had RYGBP, and one had a laparoscopic sleeve gastrectomy with a duodenojejunal bypass. Data collected included pre- and postoperative 75 g oral glucose tolerance test, daily postoperative fasting plasma glucose, and haemoglobin A1c (HbA1c) pre-operation and at two, four and 12 weeks post operation. After 12 weeks, the mean drop in HbA1c was 2.29 +/- 1.39 percent. The change in HbA1c at four (p is 0.039) and 12 (p is 0.005) weeks showed significant improvements. A significant decrease in diabetic medication usage was observed, with four (57 percent) patients not requiring medications within four weeks. Remission of DM was achieved in two (28.6 percent) patients within 12 weeks. Weight loss by various parameters was significant from two weeks onwards. The cure rate of 28.6 percent and an improvement rate of 100 percent of T2DM in morbidly obese Asian patients within 12 weeks post operation are promising. Many patients discontinued their diabetic medications in the immediate postoperative period, even before significant weight loss had occurred, indicating that RYGBP has an effect on hormonal mechanisms that influence glucose homeostasis in the body.