Side-by-side · Research reference

GLP-1 (7-37)vsIGF-1 LR3

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

AHuman-MechanisticHUMAN-REVIEWED16/43 cited

BAnimal-StrongHUMAN-REVIEWED10/58 cited

GLP-1 (7-37)

Incretin Hormone · Native Peptide

~2 minHalf-lifeAlavi 2021 Ding 2017

3297.7 DaMolecular weightAlavi 2021

1922Discovery year

Research use only · IV/SC in experimental settings

IGF-1 LR3

IGF-1 Analogue · Research

3–10×Potency vs IGF-I

Low IGFBPBinding affinity

ResearchStatus

Research only · SQ typical in animal models

01Mechanism of Action

Parameter

GLP-1 (7-37)

IGF-1 LR3

Primary target

GLP-1 receptor (class B GPCR)Koole 2015

IGF-1 receptor (IGF-1R)McTavish 2009

Pathway

GLP-1R activation → cAMP production → PKA signaling → insulin secretion (pancreatic β-cells)Lu 2025 Koole 2015

IGF-1R → IRS-1 → PI3K/Akt → Cell proliferation, protein synthesis, anti-apoptosisMuhlbradt 2009

Downstream effect

Glucose-dependent insulin release, glucagon suppression, delayed gastric emptying, reduced food intakeLu 2025 Ding 2017

Enhanced cell proliferation, muscle anabolism, inhibition of apoptosis, increased telomerase activity

Feedback intact?

Yes — physiological secretion and degradation preserved

No — exogenous IGF analogue bypasses GH-mediated regulation

Origin

Endogenous peptide cleaved from proglucagon in intestinal L cells; secreted postprandially

Synthetic 83-AA analogue: 13-AA N-terminal extension + Arg substitution at position 3

Antibody development

—

02Dosage Protocols

Parameter

GLP-1 (7-37)

IGF-1 LR3

Clinical use

None — native GLP-1 not used therapeutically

Engineered analogues (semaglutide, liraglutide) used clinically.Friedman 2024

—

Research dosing

Variable — 0.1–10 nmol/kg in animal models

Used as reference standard for analogue comparison.

—

Half-life

~2 minutes (plasma)Alavi 2021 Ding 2017

Requires continuous infusion for sustained effect.

—

Modified analogues

t½ extended to 13 h (liraglutide), 165 h (semaglutide)

Via DPP-4 resistance + fatty acid acylation.

—

Research dose (animal models)

—

Variable by protocol and species

In vivo murine atherosclerosis studies used sustained delivery.

In vitro typical concentration

—

10–1000 ng/mLThomas 2007

Dose-dependent effects on follicle growth and estradiol production.

Half-maximal stimulation

—

0.6 nM LR3 vs 1.5 nM native IGF-1Price 2004

2.5-fold greater potency in lung fibroblast proliferation.

Evidence basis

—

Animal / in vitro only

Human use

—

Not FDA-approved; no published human trials

03Metabolic / Fat Loss Evidence

Parameter

GLP-1 (7-37)

IGF-1 LR3

Mechanism

GLP-1R activation in hypothalamic satiety centers (arcuate nucleus) reduces food intakeLu 2025

Effect demonstrated with long-acting analogues (liraglutide).Lu 2025

IGF-1R activation → lipolytic signaling; secondary to anabolic effects

Native GLP-1 efficacy

Minimal — rapid degradation prevents sustained appetite suppression

—

Gastric emptying

Delayed in animal models, contributing to satiety

—

Body weight impact

Not observed with native GLP-1 — requires analogue formulations

—

Direct lipolytic evidence

—

Minimal — primarily anabolic/anti-apoptotic in literature

Atherosclerotic plaque effects

—

Reduced stenosis and core size in ApoE-KO micevon 2011

Plaque stabilization via vSMC phenotype modulation, not direct fat loss.

Human data

—

None published

04Side Effects & Safety

Parameter

GLP-1 (7-37)

IGF-1 LR3

Native GLP-1

Well-tolerated in research settings; no prolonged exposure data

—

Hypoglycemia risk

Low — insulin secretion is glucose-dependent

Theoretical — IGF-1 analogues can lower blood glucose

Analogue side effects

Nausea, vomiting, diarrhea (GLP-1R agonists)

Not applicable to native GLP-1 due to non-therapeutic use.

—

GLP-1 resistance

High glucose-induced PKCβ overexpression may reduce GLP-1 responsiveness in endothelial cellsPujadas 2016

—

Excessive cell proliferation

—

Mitogenic signaling; theoretical tumor promotion risk

Telomerase activation

—

2–10-fold increase in prostate cancer cells (PC-3, DU-145, LAPC-4)Wetterau 2003

Critically involved in cancer cell immortalization.

Oocyte degeneration

—

Increased oocyte degeneration at high doses (≥1000 ng/mL) in bovine folliclesThomas 2007

Unregulated anabolism

—

Bypasses physiological GH/IGF-1 feedback; no pulsatility control

Unknown human safety profile

—

No published human trials; safety data absent

Absolute Contraindications

GLP-1 (7-37)

—

IGF-1 LR3

·Active malignancy or history of cancer
·Not approved for human use

Relative Contraindications

GLP-1 (7-37)

—

IGF-1 LR3

·Diabetes or glucose intolerance
·Family history of cancer

05Administration Protocol

Parameter

GLP-1 (7-37)

IGF-1 LR3

1. Research use only

Native GLP-1(7-37) is not formulated for therapeutic use. Administered IV or SC in experimental protocols to study GLP-1R pharmacology and as reference standard for analogue development.

IGF-1 LR3 is not FDA-approved for human use. All administration data derives from animal or in vitro studies.

2. Storage

Lyophilised peptide stored at -20°C or below. Reconstituted solutions should be prepared fresh and used immediately due to rapid degradation.

Subcutaneous or intraperitoneal injection in animal models. In vitro: added directly to culture medium at concentrations of 10–1000 ng/mL.Thomas 2007

3. Clinical alternatives

For therapeutic GLP-1R activation, use FDA-approved long-acting analogues: semaglutide (once weekly), liraglutide (once daily), dulaglutide (once weekly), or exenatide (twice daily or once weekly).

Lyophilised powder reconstituted in sterile water or buffered saline per manufacturer protocol. Store at 2–8 °C after reconstitution.

4. Stability

—

Enhanced stability vs native IGF-1 due to reduced IGFBP binding; exact half-life in vivo not fully characterized in humans.

06Stack Synergy

GLP-1 (7-37)

— no documented stacks

IGF-1 LR3

+ GHRP-6

Multi-pathway

View GHRP-6 →

GHRP-6 stimulates endogenous GH release, which drives hepatic IGF-1 synthesis. IGF-1 LR3 provides exogenous, IGFBP-resistant IGF signaling. Combining upstream GH stimulation with downstream IGF receptor activation creates a dual-pathway anabolic effect. However, this bypasses natural feedback and carries compounded mitogenic risk.

GHRP-6: 100–200 mcg SQ · 2–3× daily
IGF-1 LR3: Research doses variable · post-workout typical in animal models
Note: Research context only — no human protocols exist
Primary benefit: Theoretical maximal anabolic signaling (GH + IGF axes)

+ Ipamorelin

Multi-pathway

View Ipamorelin →

Ipamorelin (selective GHRP) stimulates pulsatile GH release without cortisol/prolactin elevation. IGF-1 LR3 directly activates IGF-1R independent of GH. This stack targets both upstream (GH secretion) and downstream (IGF receptor) nodes but eliminates physiological feedback, raising safety concerns around unchecked proliferation.

Ipamorelin: 200–300 mcg SQ · evening
IGF-1 LR3: Research doses only · timing variable
Caution: No human data; animal/in vitro only
Primary benefit: Dual-axis anabolic signaling (theoretical)