Sarah Evans, MD, Zehra Pamuklar, MD, Jonathan Rosko, RN, Patrick Mahaney, RD, Ning Jiang, MD, Chan Park, MD, Alfonso Torquati, MD. Duke University, Department of Surgery
INTRODUCTION – This study investigated the effects of gastric bypass surgery (GBS) on the postprandial levels of anorexigenic gut hormones. Our primary hypotheses were that obese individuals with type 2 diabetes mellitus (T2DM) lack significant postprandial stimulation of polypeptide YY (PYY), and glucagon-like peptide-1 (GLP-1) and this response is restored after GBS independently of caloric restriction.
METHODS AND PROCEDURES – PYY and GLP-1 were measured in the fasting state and at different time points after a standardized liquid meal in two matched groups of obese subjects with T2DM treated only with oral hypoglycemic medications. The meal stimulation test was performed before and after (12 ± 4 days ) the two study interventions: Group 1 (n=10) – Gastric Bypass Surgery (GBS); Group 2 Control (n=10) – Caloric restriction by liquid diet matching post–GBS diet.
RESULTS – The two groups were successfully matched for sex (3M/7F in both cohorts), age (Control = 46.3 ± 6.5 years, GBS = 49.6 ± 11.1 years), and preoperative BMI (Control = 44 ± 8.9, GBS =45.6 ± 7.6). The magnitude of post-intervention change in BMI was similar in the two groups (-2.9 in GBS and -2.4 in Controls). However, excess weight loss was significantly higher (P<0.01) in the GBS group (14.2%) than in the Control group (7.2%).
As shown in the Figure, patients following GBS had a significantly (P=0.01) increased postprandial plasma levels of PYY and GLP-1 favoring enhanced satiety than obese controls with matched caloric restriction.
CONCLUSIONS – At baseline, the entire obese cohort in our study had a blunted postprandial PYY and GLP-1 response, which may reflect a functional deficiency state. However, following GBS there is a significant restoration of the postprandial stimulation of PYY and GLP-1 that is clearly independent from caloric restriction. The phenomenon of ‘bariatric surgery-induced anorexia’ may be potentially linked to the increased postprandial levels of PYY, and GLP-1 observed after GBS.
Program Number: S088