Endocrine Abstracts

Background: Changes in gut hormone levels after laparoscopic sleeve gastrectomy (LSG) has been proposed as a possible mechanism that explains the long-term weight loss and the improvement in glucose homeostasis after bariatric operations. In this prospective study we evaluated the changes in the fasting and postprandial levels of glucagon like peptide-1 (GLP-1), peptide YY (PYY), insulin and glucose during the first postoperative year after LSG.

Methods: Twelve morbid obese patients (three male, nine female, mean BMI 46.7±6.59) were evaluated preoperatively and 6 weeks, 6 months and 12 months postoperatively. None of the patients had established diabetes preoperatively, however 85.7% of them (10/12) were insulin resistant. A standard 75 g oral glucose tolerance test (OGTT) was given after an overnight fast and blood samples were collected before and 30, 60, 90, 120 min after the OGTT for measurement of GLP-1, PYY, insulin and glucose.

Results: Body weight, body mass index (BMI) and waist circumference decreased markedly after LSG (all, P<0.0001). GLP-1 and PYY fasting levels did not change significantly postoperatively. GLP-1 and PYY postprandial responses as measured by Area Under the Curve (AUC) were significantly higher from the sixth postoperative week (P<0.0001). Fasting insulin levels were lower from 6 weeks postoperatively (P<0.0001), while insulin AUC decreased at 6 and 12 months postoperatively (P=0.0093). Finally, glucose AUC decreased at 6 and 12 months (P<0.0001) but glucose fasting levels decreased only at 12 months postoperatively (P=0.0091). Insulin sensitivity measured by Matsuda Index increased progressively postoperatively (P<0.0001) when the early insulin secretion measured by insulinogenic index did not change (P=0.21).

Conclusion: After LSG, GLP-1 and PYY postprandial responses in obese non- diabetic patients increased after an oral glucose tolerance test and was maintained for at least one year. Glucose and insulin levels decreased postoperatively showing a significant improvement in glucose homeostasis after LSG.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.