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Roux-en-Y lowered plasma glucose concentrations, misrepresented beta-cell function
Despite the benefits of Roux-en-Y gastric bypass surgery, researchers have discovered it could cause decreased plasma glucose concentrations in the third hour of an oral glucose tolerance test and misreported beta-cell function.
Six morbidly obese patients without diabetes were included in the study in which Christian-Heinz Anderwald, MD, MPHARM, MBA, of the metabolic unit of the Institute of Biomedical Engineering at the National Research Council (ISIB-CNR) in Padua, Italy, and colleagues sought to determine the effects of Roux-en-Y gastric bypass (RYGB) surgery on gastrointestinal, endocrine and metabolic alterations. They compared preoperative and postoperative patients.
The researchers said postoperative patients lost 35 kg body weight (P<.0001) in roughly 6 months. Whole-body insulin sensitivity (M/I) increased after surgery and was related to fat mass (P<.0001). Additionally, during OGTT, postoperative patients showed a ≥15% decrease in plasma glucose from 120 to 180 minutes (≤4.5 mmol/L). This finding was in conjunction to a 29-fold elevated active glucagon-like peptide-1 dynamic area under the curves, which was linked to an 84% increase in beta-cell secretion (P<.001).
Further data indicated insulin-stimulated insulin secretion in the postoperative group was 52% higher compared with preoperative patients, but 1 pmol/min2 to 2 pmol/min2 lower compared with the obese control group and lean control group (P<.05).
The researchers said basal hepatic insulin sensitivity improved at fasting, but insulin mediated hepatic glucose production suppression remained unchanged and prolonged. Also, insulin secretion during hyperinsulinemia was higher after, compared with before, surgery. However, it was still worse compared with matching controls.
“This suggests that in RYGB patients, augmented GLP-1 secretion and slightly lower gut glucose absorption in general (which was also present before the surgery), as well as to some (minor) extent, improved basal hepatic insulin sensitivity with reduced fasting insulin secretion are the main contributors to the observed gastrointestinal, endocrine, and metabolic alterations, which are mostly beneficial, but also include unwanted, and thus threatening, effects, such as pronounced post-prandial hypoglycemia,” the researchers wrote.
Disclosure: Anderwald report no relevant financial disclosures. See study for full text of relevant financial disclosures.