The obesity and type 2 diabetes mellitus (T2DM) are among the most threatening health crisis for the 21st century. Currently, it is estimated that there are 205 million people with T2DM worldwide. Chile has a similar magnitude of problem with the prevalence of diabetes increasing from 6.3% in 2003 to 9.4% in 2010. T2DM is a complex disease characterized by hyperglycemia, insulin resistance and a relative β-cell failure. Well-known studies for the treatment of T2DM (ADVANCE trial) showed that intensive medical treatment significantly reduces the complication of diabetes. On the other hand, less than 40% of patients with T2DM achieve a metabolic control of diabetes, despite medical treatment. Recently, bariatric surgery has emerged as an effective treatment for T2DM. Data from different sources has shown that Roux-en-Y Gastric Bypass (RYGB) can place T2DM into remission. More recently, Sleeve Gastrectomy (SG) has been shown to also impact metabolically and hence also emerged as an attractive T2DM-controlling bariatric procedure with fewer complications than RYGB. Recently, the International Federation for Diabetes has supported the use gastrointestinal surgery initially developed for morbid obesity as an option to treat patients with diabetes. In the current proposal the investigators aim to address several issues concerning metabolic surgery and the ability of the most common bariatric procedures performed to control diabetes. The investigators are proposing a prospective randomized trial comparing RYGB, SG and the best medical treatment availed for the T2DM in poorly control patients with the primary endpoint being 36 month glycemic control (patients achieving HbA1C < 6.5%, normal glucose levels not requiring medication). The main working hypothesis is that RYGB and SG achieves better glycemic control than the best treatment availed for the T2DM based on more effective mechanisms to enhance insulin secretion, insulin sensitivity, lipid metabolism and blood pressure control. The goals are, 1) Is gastric bypass surgery and sleeve gastrectomy safe for the microvascular complications of T2DM?; 2) Can gastric bypass, sleeve gastrectomy surgery and intensive non surgical treatment reverse or reduce the progression of microvascular complications of T2DM?; and 3) Can gastric bypass and sleeve gastrectomy realize a return on investment within 2 years in patients with type 2 diabetes who are at risk of developing or deteriorating microvascular complications?