The Effects of an Amino Acid Supplement on Glucose Homeostasis, Inflammatory Markers, and Incretins after Laparoscopic Gastric Bypass

BACKGROUND: Protein supplements are routinely used after a laparoscopic gastric bypass (LGB). The aim of this study was to evaluate the impact of an amino acid supplement on glucose homeostasis and hormonal and inflammatory markers after LGB. STUDY DESIGN: Thirty patients undergoing LGB were randomized to receive or not 24 g of an oral supplement containing a leucine metabolite, glutamine, and arginine twice daily. Changes in weight, glucose, insulin, C-peptide, insulin sensitivity, interleukin (IL) 6, C-reactive protein (CRP), leptin, insulin-like growth factor (IGF) 1, ghrelin, and incretins were assessed preoperatively and 2 weeks and 8 weeks postoperatively. RESULTS: Thirty patients (96.7% female, age 46.9 +/- 8.4 years, body mass index 43.3 +/- 4.1 kg/m(2)) were randomized. The experimental (n = 14) and control (n = 16) groups were not significantly different at baseline. Weight loss was similar for the 2 groups. Fasting glucose decreased significantly at 2 and 8 weeks compared with base line (p < 0.0001) with no difference between the experimental and control groups (p = 0.8), but insulin and calculated insulin sensitivity, which were similar at baseline, became significantly worse in the experimental group 8 weeks after surgery (p = 0.02 for insulin; p = 0.04 for the homeostasis model assessment of insulin resistance). CRP and IL-6, which were similar at baseline, were found to be significantly higher at 8 weeks in the experimental group (p = 0.018 and p = 0.05, respectively). Leptin and IGF-1 levels decreased significantly from baseline at 2 and 8 weeks (p < 0.0001), but there was no difference between the 2 groups. No significant changes in GLP-1, ghrelin, or gastric inhibitory polypeptide were noticed after 8 weeks. CONCLUSIONS: An amino acid supplement had no effect on the early postoperative incretins after LGB. It may have a negative influence on glucose kinetics and degree of inflammation. Future studies are needed to clarify these effects. (J Am Coll Surg 2011;212:617-627. (C) 2011 by the American College of Surgeons)