Glucagon-Like Peptide 1 (GLP-1)

Clinical Significance:
Glucagon-Like peptide 1 (GLP-1) has two forms of 31 and 37 amino acids produced in the small intestine and in the pancreas in humans. GLP-1 is processed from its precursor, proglucagon, in the pancreatic cells and is a stimulator for insulin secretion in vitro and in vivo (1). GLP-1 amide is present in many brain regions and may paly a role in the physiological control of feeding implicated in satiation and food intake regulation (2). Exogenous GLP-1 lowers postprandial glycaemia by slowing gastric emptying, glucagon secretion and food intake (3). The use of exogenous GLP-1 as an agonist for the GLP-s receptors has been widely used in the management of type 2 diabetes and obesity (4).

Test validated for clinical use.

Reference Range:
Fasting: up to 50 pmol/L

Procedure:
GLP-1 is measured by radioimmunoassay 

Patient Preparation:
Patient should be fasting 10 – 12 hours prior to collection. Patient should not be on any medications that influence insulin secretion or intestinal motility if possible.

Specimen Collection:
Collect using EDTA plasma collection tube OR 10mL blood directly into ISI’s G.I-tubeTM preservative, and separate as soon as possible. Freeze plasma immediately after separation. Special G.I.-tubeTM preservatives are available from ISI. Minimum specimen size is 1 ml.

Shipping Instructions:
Ship specimens strictly frozen in dry ice. 

References:
1. Whalley NM, Pritchard LE, Smith DM, White A. Processing of proglucagon to GLP-1 in pancreatic α-cells: is this a paracrine mechanism enabling GLP-1 to act on β-cells?. J Endocrinol. 2011;211(1):99-106. doi:10.1530/JOE-11-0094

2. Meloni AR, DeYoung MB, Lowe C, Parkes DG. GLP-1 receptor activated insulin secretion from pancreatic β-cells: mechanism and glucose dependence. Diabetes Obes Metab. 2013;15(1):15-27. doi:10.1111/j.1463-1326.2012.01663.x

3. Maselli DB, Camilleri M. Effects of GLP-1 and Its Analogs on Gastric Physiology in Diabetes Mellitus and Obesity. Adv Exp Med Biol. 2021;1307:171-192. doi:10.1007/5584_2020_496

4. Prasad-Reddy L, Isaacs D. A clinical review of GLP-1 receptor agonists: efficacy and safety in diabetes and beyond. Drugs Context. 2015;4:212283. Published 2015 Jul 9. doi:10.7573/dic.212283