Metabolic consequences of the incorporation of a Roux limb in an omega loop (mini) gastric bypass: evaluation by a glucose tolerance test at mid-term follow-up.

backgroundIn the technique used in our department, Roux-en-Y gastric bypass (RYGB) anatomically only differs from the mini- or omega loop gastric bypass (OLGB) by the incorporation of an isolated alimentary limb, called the Roux limb. The metabolic consequences of the incorporation of a Roux limb are unknown.

objectivesTo evaluate differences in glucose and insulin dynamics between RYGB and OLGB in normoglycemic patients, by submitting them to a glucose challenge after stabilization of their weight.

methodsNondiabetic patients who had undergone OLGB 4 years earlier were matched with nondiabetic patients who had undergone RYGB around the same time and with healthy controls. Participants underwent oral (OGTT) and intravenous glucose tolerance test (IVGTT). Endpoints of the study were: progression of plasma glucose and insulin, changes in their concentration [calculated by area under the curve (AUC)] at OGTT and IVGTT, incretin effect and incidence of hypoglycemia.

resultsEach of the three groups comprised 14 participants. At OGTT, plasma glucose and insulin incremental values were comparable after OLGB and RYGB, and substantially higher than in controls. Overall glucose concentration, however, did not vary across the three groups. Thirty-minute and overall insulin plasma concentration, indicators of early and total insulin secretion, respectively, was significantly higher in both bypass groups than in controls, and was greatest in OLGB. Severe hypoglycemia occurred in one out of two patients in both bypass groups. At IVGTT, no differences were registered across the three groups and no participant experienced hypoglycemia. The incretin effect was higher after OLGB than after RYGB, but the difference was not statistically significant.

conclusionsThe incorporation of a Roux limb in a loop gastric bypass appears to create a statistically nonsignificant tendency toward reducing insulin hypersecretion observed at OGTT after OLGB, and consequently toward tapering the incretin effect.