Endocrine Abstracts

Obesity represents an important risk factor for type 2 diabetes mellitus (T2DM) development. The outcomes of both bariatric and metabolic surgery have provided new insights into the mechanisms responsible for body weight control and glucose homeostasis. However, at the same time the marked effects of metabolic surgery on T2DM highlights the limitations of our current knowledge underscoring the need to continue addressing relevant questions as regards the underlying mechanisms and their precise contribution in each case. As expected, weight loss improves the major factors involved in the pathogenesis of T2DM, namely insulin action and β cell function. Interestingly, over the past decades bariatric surgical procedures that divert nutrients away from the upper gastrointestinal system are more successful in producing weight loss and remission of T2DM than those that simply restrict stomach capacity. Moreover, the almost immediate beneficial effects on glucose homeostasis following bariatric surgery when no substancial change in body weight has taken place points to the existence of relevant weight loss-independent factors. This statement is based primarily on the following findings: i) the early postoperative effects of especially some types of bariatric surgery on glycemic control; ii) the long-term efficacy of different surgical procedures on T2DM resolution; iii) the effect of the duodenal-jejunal bypass (DJB), which greatly influences glucose homeostasis despite minimal weight loss; and iv) the rapid and specific hormonal response to glucose or mixed meal ingestion. Circulating insulin levels represent a summation of events that involve both β cell and non-β cell metabolic pathways. Furthermore, BMI and total body weight do not reflect differences in body composition and adiposity distribution, thereby ignoring the relationship between the different compartments (fat, muscle, liver, etc.) and metabolic risk. More research is needed to make definitive conclusions on the precise and probably multifactorial causes backing metabolic surgery effectiveness.