Fasting Glucagon-Like Peptide-1 (GLP-1)
GLP-1 is an incretin peptide hormone secreted by intestinal enteroendocrine L-cells in response to luminal nutrients, potentiating glucose-dependent insulin secretion.
Standard vs. Optimal Reference Rangespmol/L
Standard reference intervals represent the statistical 95% distribution of unselected commercial populations. Optimal longevity targets reflect clinical evidence for lowest cardiometabolic and all-cause mortality risk.
Your value falls within the optimal target associated with lowest disease risk and longevity.
1.5 - 8.5 pmol/L (Fasting Active GLP-1)
General reference distribution across unselected commercial populations.
> 5.0 pmol/L (Intact postprandial augmentation)
Concentration target associated with minimal all-cause cardiometabolic mortality.
Molecular Mechanism & Clinical Purpose
Binds the GLP-1 receptor on pancreatic beta-cells, stimulating adenylyl cyclase and cAMP to trigger insulin vesicle exocytosis. Also slows gastric emptying and stimulates central hypothalamic POMC neurons to induce satiety.
Differential Diagnosis
Elevated Levels (GLP-1 High)
- •Postprandial nutrient stimulation
- •Therapeutic GLP-1 receptor agonist therapy (e.g. semaglutide, tirzepatide)
Low Levels (GLP-1 Low)
- •Metabolic syndrome / Obesity with blunted incretin response
- •Dipeptidyl peptidase-4 (DPP-4) hyper-activity
Technical Reference & Deep Dive
Biochemistry & Enzymatic Pathways
Longevity Risk Architecture & Epidemiology
Pre-Analytical Caveats & Diagnostic Workup
Pre-Analytical Considerations:
Strict 10 to 12 hour overnight water-only fasting is mandatory for baseline metabolic quantification. Acute psychological stress, acute infectious illness, and sleep deprivation (<6 hours) transiently elevate cortisol and catecholamines, falsely elevating glycemic markers. For glucose and insulin testing, draw blood into sodium fluoride/potassium oxalate tubes or separate serum promptly within 30 minutes to prevent ongoing in vitro red blood cell glycolysis.
Reflexive Testing Protocol:
- Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and HOMA-Beta calculations
- Continuous Glucose Monitoring (CGM) 14-day wear to evaluate glycemic variability and postprandial excursions
- Fasting C-Peptide and high-sensitivity Troponin/hs-CRP to differentiate insulin resistance from beta-cell exhaustion
- Oral Glucose Tolerance Test (OGTT) with simultaneous 0, 30, 60, and 120-minute insulin assays
- Abdominal ultrasound or FibroScan to evaluate hepatic steatosis and non-alcoholic fatty liver disease (MASLD)
Clinical Citations & Primary Literature (1)
- [1]The Incretin System: GLP-1 and GIP in Metabolic Health and Disease - Lancet Diabetes & Endocrinology (2022). PMID: 35196425
Associated Longevity Guides & Clinical Calculators
Medicine 3.0Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate Fasting Glucagon-Like Peptide-1 (GLP-1) into overall healthspan optimization.