Weight loss is thought to be caused by bariatric surgery due to gastric restriction, intestinal malabsorption, or both. Adjustable gastric banding (AGB) and other restrictive surgeries limit functional stomach capacity and delay gastric emptying. Biliopancreatic diversion (BPD) is a malabsorptive operation that leaves the stomach mostly intact but diverts ingested food to the ileum, leaving just a tiny part of the colon to absorb nutrients. The usual proximal Roux-en-Y gastric bypass (RYGB) combines gastric restriction with nutritional bypass of the majority of the stomach and a short segment of the proximal intestine (mainly the duodenum); the small bowel remaining is adequate to prevent clinically severe malabsorption. Weight loss is caused by stomach constriction, as well as other mechanisms such as changes in gut hormones and other processes that are still being studied (4–15). RYGB and BPD yield the greatest and fastest rates of type 2 diabetic mellitus (T2DM) remission among bariatric operations. Several traditional bariatric surgery treatments have been shown to result in long-term remission of type 2 diabetes mellitus (T2DM); new gastrointestinal surgical approaches have also been shown to have comparable results. Other metabolic disorders, such as hyperlipidemia and hypertension, are significantly improved by these operations in both obese and nonobese individuals. Several investigations have shown evidence that these metabolic consequences are due in part to endocrine changes caused by surgical modification of the gastrointestinal system, rather than merely being the result of significant weight reduction and reduced calorie intake. We present an overview of the clinical data that shows the impact of such interventions—also known as metabolic surgery—on T2DM in this Review, as well as explore the implications for future study. We suggest that the gastrointestinal system may have a role in the pathogenesis of T2DM and obesity, based on the information given here. Several studies have shown evidence that these metabolic effects are attributable in part to endocrine changes generated by surgical gastrointestinal system modifications, rather than just being the result of large weight loss and reduced calorie consumption. In this Review, we provide an overview of the clinical evidence demonstrating the efficacy of such interventions—also known as metabolic surgery—on T2DM, as well as discuss the implications for future research. Based on the findings presented here, we believe the gastrointestinal system may have a role in the pathophysiology of T2DM and obesity. Faced with the growing worldwide diabetes pandemic, health care practitioners need as many treatment measures as they can muster. Various forms of gastrointestinal (GI) surgery, in addition to behavioural and medicinal methods, are incredibly potent choices for treating diabetes in severely obese people, sometimes stabilising blood glucose levels without the need of diabetic drugs.
