Sleeve gastrectomy leads to caloric restriction and a reduction of fat mass. The procedure causes a reduction in the circulating levels of adipokines, which reverses insulin resistance. Bariatric surgery of any form, thus, has a short- and long-term impact on blood glucose levels. The short-term impact is because of the decreased stimulation of the entero-insular axis secondary to decreased calorie intake, and the long-term effect is mediated by reduced fat mass.
Bariatric surgery leads to the resolution of T2DM within a week, prior to the significant weight loss that occurs over several months. This finding demonstrates that weight-independent factors are involved in the resolution of diabetes. Several hypotheses for the cause of this observation have been put forward, including caloric restriction and hormonal changes. Initially, it was thought that the exclusion of the foregut leads to a reduction in gastric inhibitory polypeptide hormone levels, which leads to a reduction in insulin resistance. This hypothesis formed the basis for procedures such as gastric bypass and biliopancreatic diversion. Later studies revealed the increased importance of proximal transposition of the distal ileum to be the more important factor determining the resolution of diabetes.
Procedures such as ileal interposition result in elevated basal and meal-stimulated enteroglucagon levels, a precursor for glucagon-like peptide-1 (GLP-1). Reorganization of the intestinal tract with such surgeries results in concentrated chyme being delivered to the distal ileum. Edward Mason, the “father of bariatric surgery,” stated that “ileal transposition may be an ideal surgical treatment for obese patients (and diabetics) because the surgery would be expected to significantly enhance endogenous levels of GLP-1 without the malabsorptive consequences of the other surgical methods.” These surgical procedures lead to an increase in basal as well as postprandial GLP-1 levels, and the effect is sustained over years.
GLP-1 is an intestinal hormone that is encoded in the proglucagon gene, produced by the enteroendocrine L cells of the distal ileum and colon and secreted into the blood stream upon ingestion of food containing lipids, proteins, and glucose. GLP-1 aids in the augmentation of glucose-induced insulin secretion. Continuous GLP-1 receptor activation increases insulin synthesis and pancreatic β cell proliferation and neogenesis.
The actions of GLP-1 have been extensively studied over the past 2 decades because the intravenous infusion or subcutaneous administration of GLP-1 increases insulin secretion and lowers blood glucose. Most important, it does so in humans suffering from diabetes. Therefore, therapeutic strategies based on activating the GLP-1 receptors on β cells and enhancing the actions of GLP-1 can lower the blood glucose level in diabetic patients.
The physiological functions of GLP-1 include increased insulin secretion from the pancreas. in a glucose-dependent manner, decreased glucagon secretion from the pancreas by engagement of a specific G-protein-coupled receptor, increased insulin sensitivity in both α cells and β cells, increased β cell mass and insulin gene expression, posttranslational processing and incretion, inhibited acid secretion and gastric emptying in the stomach, decreased food intake secondary to increased satiety in the brain, and promotion of insulin sensitivity.
If GLP-1 is administered by injection, it is released to the body even without food in the gut, and the patient experiences satiety even before eating. In the case of surgery-induced GLP-1 stimulation, satiety only occurs after some quantity of food is eaten and is associated with resultant insulin production. The slowing of gastric emptying as a result of the GLP-1 effect can be a problem for patients on injectable GLP-1, whereas combined sleeve gastrectomy resolves this issue in the surgical group.
Metabolic surgery is an effective procedure that can achieve complete resolution of diabetes in obese patients. Laparoscopic Sleeve Gastrectomy with Ileal Interposition (LSG+II) is an effective procedure to control T2DM in a nonobese (BMI <30 kg/m2) population. The present study demonstrates the effectiveness of the new Minimally Invasive Hybrid Surgery for Ileal Interposition (MIHSII) technique for the resolution of T2DM in patients with BMI <30 kg/m2.
The LSG+II procedure is typically performed entirely laparoscopically. Small-bowel approximation requires 9 endostaples. Hence, the sites for potential leakages are greater than for MIHSII. In MIHSII, the bowel approximation is performed extracorporeally through a small incision, thus avoiding 9 staples and decreasing the potential sites for leakages. Moreover, manoeuvring the entire small-intestinal segment is a difficult process when performed laparoscopically, and the entire procedure takes approximately 5 hours. When the procedure is performed extracorporeally, the small-intestinal segment can be easily viewed and measured.
The surgery is less time consuming and is easy to understand and practice. Because the incision incorporates the umbilicus, the cosmetic effects are minimal. MIHSII is theoretically the same procedure performed by Dr A. L. De Paula laparoscopically, but we performed MIHSII as minimally invasive surgery without a major incision. This procedure saves significant costs without compromising quality.
Performing ileal interposition procedures in patients with BMI >30 kg/m2. is generally not necessary because such patients may benefit by sleeve gastrectomy alone. Interposition is required in patients with BMI <30 kg/m2 because we cannot completely rely on the correction of the insulin resistance factor. Interposition is performed to increase insulin production by GLP-1. This is achieved without loss of bowel length or absorptive surface. Hence, patients do not experience dumpling syndrome or vitamin deficiency.
In our study, 80.48% of patients achieved resolution of diabetes, with HbA1c levels below 6.5%, and 48.57% of these patients experienced complete resolution. Those patients in whom diabetes was not completely resolved achieved good glycaemic control after the surgery. The study demonstrated a statistically significant reduction in HbA1c postoperatively.
The results of our study demonstrate that MIHSII is an easy and safe technique that aids in the complete resolution of T2DM in a majority of nonobese patients. MIHSII is an innovative technique for metabolic surgery. It is an effective procedure for the resolution of T2DM in patients with a BMI <30 kg/m2 . MIHSII is safe and easy to perform.
References
Padmakumar Ramakrishnapillai, DNB; Madhukara Pai, MS; Farish Shams, MS; Praveen Kumar, PGDDM; Shaji P.G, MD; Anithadevi T.S, MSc; Sulfia P. J, MSc; Vani Krishna, MSc (2016) Effectiveness of Minimally Invasive Hybrid Surgery for Ileal Interposition (MIHSII) for the Resolution of Type 2 Diabetes, 8-9
