A prospective evaluation of the influence of three bariatric procedures on insulin resistance improvement. Should the extent of undiluted bile transit be considered a key postoperative factor altering glucose metabolism?

Abstract

IntroductionInsulin resistance (IR), the essential step in development of type 2 diabetes mellitus (T2DM), resolves quickly after bariatric surgery, but the effectiveness depends on the type of the procedure. Although the long-term influence on IR improvement is well documented, the mechanisms of the ultra-fast response after restrictive and bypass procedures require explanation.AimTo determine IR evolution from the initial preparative period to 6 months after the operation, exposing the rapid postoperative response while comparing the 3 bariatric methods, with the belief that the metabolic effect may be correlated with anatomical combinations.Material and methodsFrom January to December, 2013, a cohort of severely obese, insulin resistant individuals recruited to the prospective study underwent laparoscopic sleeve gastrectomy (SG-30), Roux-en-Y gastric bypass (RYGB-30) and one-anastomosis gastric bypass (OAGB-30). Main laboratory parameters of glucose metabolism were evaluated in fasting patients preoperatively, 4 days and 1, 3 and 6 months after surgery.ResultsWithin the whole observation period the most significant improvement in homeostasis model assessment for IR (HOMA-IR) was observed in the first 4 days after each operation. The decrease of HOMA-IR was higher (p < 0.0001) in gastric bypass groups than in patients after SG (–41%). The difference between bypass groups favors OAGB over RYGB (63 vs. –56%, p = 0.0489).ConclusionsAmong all bariatric management factors, operation type is the most important in IR improvement. The significant difference in response after SG vs. RYGB and OAGB supports the concept of metabolic competence of duodeno-jejunal exclusion. Altered bile flow after duodeno-jejunal exclusion may be responsible for enhanced glucose metabolism improvement.

Evidence That the Length of Bile Loop Determines Serum Bile Acid Concentration and Glycemic Control After Bariatric Surgery

“…However, the question arises about a plausible underlying mechanism of these associations. One difference between the three bariatric procedures analyzed in this study is the length of bile loop [7]. While the loop created during OLGB is longer than that formed during RYGB, no bile loop is made during LSG.…”

“…In contrast, LSG seems to exert less evident effect on circulating BAs or has no effect at all [20]. In our recent study, we observed the most evident improvement of insulin sensitivity after OLGB [7]. Therefore, we decided to compare the effects of various bariatric procedures (with a long or short bile loop, or without the loop) on the composition and concentration of serum BAs and glucose metabolism in morbidly obese patients.…”

“…All these procedures result not only in a weight loss but also in the resolution of hyperglycemia, insulin resistance, and T2DM, all observed within hours or days after the surgery, well before the reduction of body weight [5,6]. Although the exact mechanism underlying the beneficial effect of bariatric surgeries on glucose metabolism is still not fully understood, some evidence points to potential involvement of bile acids (BAs) [7]. BAs are a heterogeneous group of compounds with different biological functions and physicochemical properties.…”

“…During malabsorptive procedures, such as various types of gastric bypass surgeries performed commonly nowadays, a small pouch is created in the stomach, connecting it with the proximal jejunum. As a result, BAs can reach the distal intestine and be absorbed by ileocytes [7]. In turn, during a restrictive procedure, such as LSG, a large part of the stomach is removed along the greater curvature [7].…”

“…As a result, BAs can reach the distal intestine and be absorbed by ileocytes [7]. In turn, during a restrictive procedure, such as LSG, a large part of the stomach is removed along the greater curvature [7]. These modifications of intestinal passage contribute to changes in the secretion of gut hormones and peptides and may affect both the absorption of BAs and the serum concentrations thereof [16].…”