Abstract: As one of the most common bariatric surgeries performed in clinics, vertical sleeve gastrectomy (VSG) is highly efficient for treating morbid obesity and diabetes, with its underlying mechanisms elusive and controversial. More and more studies regard obesity and diabetes as a kind of gastrointestinal disease. Moreover, the fact that gastrointestinal tract is the direct target of bariatric procedures potentially makes it a key player in weight loss and blood glucose control after surgery. From this aspect,authors thus discuss the molecular mechanisms of VSG for treating type 2 diabetes mellitus in this review.