This is a long-term follow-up and interventional study in individuals who have been diagnosed with moderate to severe obesity with or without diabetes. The purpose of this study is to determine the effects of sleeve gastrectomy on weight and blood sugar control and underlying mechanisms by metabolomics, metagenomics, functional magnetic resonance imaging (fMRI) ,adipose tissue expression chip and etc.

Prevalence of obesity has been increasing rapidly worldwide. Overweight and obesity prevalence surged to 35.1% according to China Noncommunicable Disease Surveillance 2010. An estimated 44% of the burden for diabetes has been attributed to these weight problems, as well as 23% and 7-41% of the burdens for ischaemic heart disease and specific cancers. So now, obesity is a very serious disease, and it is not easy to lose weight or maintain proper weight.

With the failure of non-surgical strategies, bariatric surgery has emerged as the most effective therapeutic option for the treatment of severe obesity. From the beginning, there are a lot of types of operation which have been created and then been abandoned. Now, the most common is Roux-en-Y gastric bypass, sleeve gastrectomy (SG), gastric banding, and biliopancreatic diversion. In recent years, the international status of SG surgery gradually went up. Since 2013, SG has been recommended as the preferred option of bariatric surgery by the American Weight Loss Society. However, the underlying mechanism of SG procedure is not fully clear.

In fact, clinical and translational studies over the last decade have shown that a number of gastrointestinal mechanisms, including changes in gut hormones, neural signalling, intestinal flora, bile acid and lipid metabolism can play a significant role in the effects of this procedure on energy homeostasis. This is a long-term follow-up and interventional study in individuals who have been diagnosed with moderate to severe obesity with or without diabetes. The purpose of this study is to determine the effects of SG on weight and blood sugar control and underlying mechanisms by metabolomics, metagenomics, functional magnetic resonance imaging (fMRI) ,adipose tissue expression chip and etc.

Inclusion Criteria:

• BMI≥35kg/m2 with or without obesity complications
• BMI≥32kg/m2 with type 2 diabetes, high blood pressure, severe OSAHS, atherosclerotic plaque formation or other obesity complications
• Type 2 diabetes duration of ≤ 15 years, half of the lower limit of normal islet reserve function or more, C peptide ≥2.

Exclusion Criteria:

• had an operation for losing weight before
• serious hepatic or renal dysfunction
• mentally ill，serious tristimania，personality disturbance，disgnosia
• drug abuse or alcool abuse
• ulcer or tumor history or other high risks for surgery or serious gastrointestinal disease
• can not be follow-up，refuse to change the life-style
• type 1 diabetes mellitus
• self-care disable or no familial care
• obesity caused by drugs
• secondary obesity, such as monogenic obesity, obesity-related genetic syndrome, cushing syndrome and etc.