Fasting and Post Oral glucose GLP-1 Secretory Dynamics in Healthy men

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 824-833-GI Regulatory Peptides
Bench to Bedside
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-830
Donna Marie Lawson*1, Johannes D Veldhuis2 and Ali Iranmanesh3
1Salem VA Medical Center, Salem, VA, 2Mayo Clinic, Rochester, MN, 3VA Med Ctr, Salem, VA
Background: Physiologically insulin secretion is episodic both in fasting and fed states, and believed to be modulated by GLP-1 after food intake. Such association and pulsatile nature of insulin secretion could be suggestive of rhythmic pattern in GLP-1 release.  

Objective: To assess GLP-1 secretory properties in normal men after water and after oral glucose intake. Subjects: Eight men ages 19-60 years and BMIs 18-31 Kg/m2

Study Design: Each subject was studied on 2 randomly assigned separate occasions after an overnight fast, consisting of ingestion of either 75 grams of dextrose solution or equal volume of water.  All sessions started between the hours of 0800-0900 and continued for a total period of 6.5 hrs, with blood collected at 10-min intervals for the measurement of GLP-1 concentrations. Due to improper sample collection, GLP-1 could not be measured in 2 men on the control day.  Secretory pattern of GLP-1 was assessed by deconvolution analysis. ApEn statistics was used to assess regularity of potential GLP-1 pulses.

Results: Mean 6.5 hr circulating GLP-1 concentration (pmol/L) increased significantly from 0.596 ± 0.11 (SD) to 1.012 ± 0.26 (P=0.011) after oral dextrose ingestion. Deconvolution analysis of GLP-1 time series identified basal and pulsatile secretory events, contributing to total GLP-1 secretion both on water and glucose days. Glucose ingestion resulted in significant increases in total secretion of GLP-1 from 14.6±5.7 to 53.5±20.4 (P=0.0008) contributed by joint augmentation of basal (9.0±4.1 v 28.3±13.3: P=0.005) and pulsatile (5.6±3.2 v 25.1±8.8: P=0.0002) components. Post-dextrose increase in pulsatile GLP-1 release was primarily due to increased burst mass (1.5±0.8 v 7.5±3.3: P=0.001) with no significant change in pulse frequency (3.67±1.0 v 3.63±1.1: P=NS). ApEn of GLP-1 concentration time series decreased after oral glucose (0.770±0.12 v 0.516±0.13: P=0.003).

Conclusion: The present study revealed pulsatile pattern in circulating GLP-1 concentrations both after water and glucose ingestion. Oral dextrose markedly amplified both pulsatile and basal GLP-1 release, with burst mass as the primary contributor to augmented pulsatile component. In addition glucose intake improved regularity of GLP-1 peaks.

Nothing to Disclose: DML, JDV, AI

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Sources of Research Support: Salem V.A. Medical Center and Salem Research Institute, Salem, Virginia