Reconfiguration of the small intestine and diabetes remitting effects of Roux-en-Y gastric bypass surgery

Effect of bolus enteral tube feeding on body weight in ambulatory adults with obesity and type 2 diabetes: a feasibility pilot randomized trial

Background/objectives

To ascertain the effect on body weight of 14 days of bolus enteral feeding with mixed meal (MM) and electrolyte solution (ES) in ambulatory adults with type 2 diabetes and obesity, and also the safety and feasibility of using a modified, intraorally anchored enteral feeding tube for this purpose.

Subjects/methods

We conducted a randomized, crossover pilot trial with 16 participants. A 140 cm, 8-French feeding tube was placed in the jejunum under electromagnetic guidance and anchored intraorally. Participants were randomized to self-administer 120 mL 523 kJ (125 kcal) MM, or 50 kJ (12 kcal) ES four times/day for 14 days. After ≥14 days without the tube, participants crossed over to the other treatment. The primary outcome compared weight change between treatments. Thereafter, participants could elect to undergo additional MM cycles. Participants were encouraged to continue with all usual activities including eating ad lib throughout the study.

Results

Ten participants withdrew prior to completing two randomized 14-day cycles (4 social, 3 intolerant of anchor, and 3 intolerant of tube). Six participants were assessed for the primary outcome and showed no significant difference in weight loss between MM and ES (p = 0.082). For the secondary outcome of within-group weight loss, average weight loss from baseline was significant for MM but not for ES: −2.40 kg (95% CI: −3.78, −1.02; p = 0.008) vs. −0.64 kg (95% CI: −2.01, 0.74; p = 0.27). A total of 23 2-week cycles were completed (12 paired, 2 unpaired, and 9 additional), with no significant adverse events for 334 days of tube use.

Conclusions

Repeated bolus nutrient administration via enteral feeding tube is associated with weight loss in adults with obesity and type 2 diabetes, with no significant difference seen between MM and ES feeds. The prototype device was safe, but requires development for further investigation into the effect of bolus jejunal feeding on weight and to improve acceptability.

A new proposed mechanism of action for gastric bypass surgery: Air hypothesis

Roux-en-Y gastric bypass (RYGB) surgery is one of the most effective treatments for obesity and type II diabetes. RYGB was originally believed to work by mechanically restricting caloric intake or causing macronutrient malabsorption. However, such mechanical effects play no role in the remarkable efficacy of gastric bypass. Instead, mounting evidence shows that altered neuroendocrine signaling is responsible for the weight reducing effects of RYGB. The exact mechanism of this surgical response is still a mystery. Here, we propose that RYGB leads to weight loss primarily by inducing a functional shift in the gut microbiome, manifested by a relative expansion of aerobic bacteria numbers in the colon. We point to compelling evidence that gastric bypass changes the function of the microbiome by disrupting intestinal gas homeostasis, causing excessive transit of swallowed air (oxygen) into the colon.

Examining the gut bacteriome, virome, and mycobiome in glucose metabolism disorders: Are we on the right track?

Human gut microbiome is defined as the gene complement of the gut microbial community, measured via laboratory metagenomic techniques. It includes bacteriome, virome and mycobiome, which represent, respectively, the assemblages of bacteria, viruses and fungi, living in the human gut. Gut microbiota function as a living "organ" that interacts with the gastro-intestinal environment, provides nutrients and vitamins to the organism and transduces hormonal messages, essentially influencing the main metabolic pathways, including drug metabolism. A clear association between gut, and glucose metabolism disorders has recently emerged. Medications acting on glucose absorption in the gut, or enhancing gut hormone activity are already extensively employed in the therapy of diabetes. Moreover, the gut is characterized by immune, and autonomous neuronal features, which play a critical role in maintaining glucose metabolism homeostasis. Gut microbes respond to neuroendocrine, and immune biochemical messages, affecting the health, and behavior of the host. There is vast heterogeneity in the studies included in this review, hence a meta-analysis, or a systematic review were not applicable. In this article, we attempt to reveal the interplay between human gut microbiota physiology, and hyperglycemic states, synthesizing, and interpreting findings from human studies.