Bariatric Surgery and the Mechanism of Diabetes Remission: Are We Getting There?

Abstract

The worldwide obesity epidemic and its accompanying pathologies of type 2 diabetes mellitus and cardiovascular disease have underscored the need for effective weight-lossstrategies(1).Despiteintensiveeffortsandnumerousemergingfindings,reliableandsafepharmacological approaches that are able to effectively decrease body weight and maintain this reduction in the long run remain elusive.Bariatricsurgeryremainstheonlystrategyproven to achieve and sustain significant weight loss in patients with more severe degrees of obesity (2, 3). These procedures not only markedly reduce body weight but also radically improve diabetes control or lead to its complete remission in a high percentage of patients. Although clear metabolic improvements are evident in all patients after bariatric surgery, different types of operations appear to vary in the rate of diabetes remission as well as in the timing of metabolic improvements (4). Traditional classification of bariatric operations into restrictiveandmalabsorptiveisnowconsideredinadequateby some leaders in the field (4). Yet it still provides a basis to understand the degree of alteration in gastrointestinal tract anatomy and the mechanism of weight-loss achievement. In restrictive procedures, such as gastric banding, gastric plication,andsleevegastrectomy,decreasedfoodintakeandlongtermweightlossareachievedmainlybyconstrictingstomach size without further modifications of gastrointestinal anatomy.Inthemostmalabsorptiveprocedures(eg,biliopancreatic diversion, Roux-en-Y gastric bypass [RYGB]), stomach size is also partially restricted, and a direct connection of the stomach and the lower part of the small intestine is created. Bypass of a significant portion of the intestine then leads to decreased absorption of nutrients, resulting in weight loss. The rate of diabetes remission after different types of bari