Background: The prevalence of obesity has increased significantly in the last decades. Epidemiological studies confirmed the association of increasing obesity trends along with a high prevalence of type 2 diabetes mellitus (T2DM). Losing weight is a cardinal step to achieve better glycemic control when treating diabetic patients. Besides medical therapy, bariatric surgery has been considered as an option for obtaining the remission of T2DM. Objective: To review the published literature that discusses the effect of bariatric surgery on T2DM. Method: PubMed database was used for article selection, and the following keys were used in the mesh ((“bariatric surgery” [Mesh]) and (“type 2 diabetes mellitus” [Mesh])). The article selection was based on the relevance to the topic as their primary endpoint. Conclusion: The idea behind the positive effects of bariatric surgery in treating diabetes is not only because of weight loss alone. Changes in the responsiveness of beta cells, in incretins levels, and bile salts regulation also have effects on diabetes. A considerable number of randomized clinical trials have been evaluating the safety and the efficacy of the different bariatric procedures such as vertical sleeve gastrectomy (VSG), Roux-en-Y gastric bypass (RYGB), and biliopancreatic diversion/duodenal switch (BPD/DS) in treating T2DM. These procedures have shown to be associated with better outcomes regarding diabetes control and higher remission rates than medical therapy.