IGF-Des: A Literature Course on Des(1-3)IGF-I Research

IGF-Des is an informal name for des(1-3)IGF-I (also printed as des(1-3)IGF-1 or des-IGF-1), a shortened form of insulin-like growth factor I. This page is a six-module reading course that summarises what the published literature describes, module by module, and closes with the questions the studies did not address. This page is for educational purposes only and is not medical advice; consult a licensed physician for any question about health, diagnosis or treatment. Nothing here describes how a compound should be used, and no outcome is presented as a benefit that can be expected.

Module 1: What IGF-Des Is and How It Has Been Studied

Insulin-like growth factor I is a single-chain polypeptide of 70 amino acids. The des(1-3) variant lacks the first three N-terminal residues — glycine, proline and glutamate — leaving a 67-residue molecule. It belongs to the class of recombinant growth-factor analogues rather than to short synthetic peptides such as secretagogues, and it is produced by recombinant expression rather than by solid-phase synthesis at scale.

The analogue is usually discussed alongside two other engineered IGF-I forms. A 2021 analytical paper grouped LongR³-IGF-I, Des(1-3)-IGF-I and R³-IGF-I together as IGF-I analogues and described an immunopurification plus high-resolution mass spectrometry workflow for detecting them for antidoping purposes (PMID 33587816). That paper is one of the clearest indications of how the molecule is encountered in practice: as an identifiable analytical target distinguishable from native IGF-I.

Study formats in the literature

• Cell culture: human stromal cells from benign prostatic hyperplasia tissue (PMID 12573816), human retinal endothelial cells (PMID 11691647) and porcine myotubes carrying a MYH4 promoter reporter (PMID 33614996).
• Ex vivo tissue: rat hippocampal slices used to characterise des-IGF-1 action at excitatory synapses in the CA1 region (PMID 15985695) and articular cartilage explants used to study IGF-I transport and binding (PMID 12801514).
• Animal models: diabetic rats examined at a predegenerative retinal stage (PMID 12745670), transgenic mice carrying mutant p53 together with des(1-3)IGF-I (PMID 10702797), and cats with naturally occurring diabetes mellitus studied for IGFBP-3 ternary complex regulation (PMID 10856879).

Limits of the evidence for Module 1: this body of work is preclinical and analytical. The verified literature contains no randomised human trial of IGF-Des, no standardised product description and no consensus nomenclature, which means results published under "des(1-3)IGF-I", "des-IGF-1" and related spellings are not always directly comparable.

Module 2: Mechanism as Described in the Literature

The mechanistic account in published papers rests on two ideas: receptor activation and binding-protein interaction.

Receptor and downstream signalling

Studies treat des(1-3)IGF-I as a ligand for the type 1 IGF receptor. In diabetic rats, researchers reported that des(1-3)IGF-1 treatment normalised type 1 IGF receptor and phospho-Akt (Thr 308) immunoreactivity in predegenerative retina (PMID 12745670), which places the analogue within the canonical IGF-1R/PI3K/Akt pathway. In pituitary tissue, researchers characterised IGF-I receptors and reported that IGF-I signalling modulated prolactin and growth hormone release in that preparation (PMID 12121860), illustrating that IGF receptor engagement is not confined to peripheral growth tissues.

Binding proteins

Native IGF-I circulates bound to IGF-binding proteins. A study of human retinal endothelial cells reported that IGFBPs modulated cell growth driven by IGF-I and by high glucose (PMID 11691647), showing that the binding-protein layer, not receptor affinity alone, shapes the cellular response. In cats with diabetes mellitus, researchers examined regulation of the IGFBP-3 ternary complex and reported disease-associated differences in that complex (PMID 10856879). Because the N-terminal tripeptide removed in des(1-3)IGF-I sits in the region that contributes to binding-protein interaction, the analogue is used in experiments as a comparator that is less constrained by IGFBPs than the intact molecule.

Limits of the evidence for Module 2: most mechanistic statements come from single-tissue systems. The verified papers describe receptor immunoreactivity, phosphorylation markers and growth responses; they do not map a full dose-response relationship for the analogue in intact humans, and they do not establish which downstream pathway predominates in any given tissue.

Module 3: Reported Outcomes by Study

The table below summarises the model, endpoint and reported finding for each study in this evidence set. None of these findings is a promise of benefit; several are neutral or unfavourable.

Two observations follow from the table. First, the endpoints are heterogeneous: immunoreactivity, synaptic physiology, proliferation, promoter activity and tumour latency are not interchangeable measures. Second, the direction of effect depends entirely on the tissue. A signalling normalisation reported in diabetic rat retina (PMID 12745670) and a growth stimulation reported in prostate stromal cells (PMID 12573816) reflect the same underlying growth-factor biology producing different consequences.

Limits of the evidence for Module 3: these are separate experiments with different species, exposure routes and durations, and none of them measured a clinical outcome such as strength, body composition, vision or survival in people. No study in this set compared IGF-Des against intact IGF-I in a human population.

Module 4: IGF-Des Side Effects: What Studies Report

There is no clinical adverse-event table for IGF-Des in the verified literature — no human safety trial appears in this evidence set. What the published work does report are biological hazards observed in laboratory models.

Proliferative and tumour-related findings

The most direct hazard signal comes from a mouse study in which researchers reported that mutant p53 and des(1-3)IGF-I acted cooperatively to accelerate mammary tumorigenesis (PMID 10702797). A second proliferative finding was reported in human benign prostatic hyperplasia stromal cells, where the study described des(1-3)IGF-I-stimulated cell growth that a vitamin D3 analogue inhibited (PMID 12573816). A third line of work reported that IGF-I- and high glucose-controlled growth of human retinal endothelial cells was modulated by IGFBPs (PMID 11691647), a system relevant to proliferative retinal disease.

Endocrine and neural findings

Endocrine effects reported in this set are not framed as adverse events but are relevant to systemic exposure: researchers reported that IGF-I receptor signalling in pituitary tissue modulated prolactin and growth hormone release (PMID 12121860). In neural tissue, the study of des-IGF-1 at CA1 excitatory synapses characterised functional changes in synaptic transmission (PMID 15985695) rather than toxicity.

Limits of the evidence for Module 4: hazard findings in transgenic mice and isolated human cells do not establish incidence, severity or reversibility in people. No study here monitored hypoglycaemia, injection-site reactions, immunogenicity or long-term organ effects, and the absence of reported adverse events in a preclinical paper is not evidence of safety.

Module 5: Pharmacokinetics and Delivery, Where Data Exist

Formal human pharmacokinetic parameters — absorption, half-life, clearance — are not available for IGF-Des in this evidence set. What exists is adjacent transport and distribution work on IGF-I and on protein delivery generally.

• Blood–brain barrier: researchers examined the interactions of IGF-1 with the blood–brain barrier in vivo and in situ and reported the transport and binding behaviour of the growth factor at that interface (PMID 11025411).
• Cartilage penetration: a study of transport and binding of IGF-I through articular cartilage reported that binding interactions within the matrix shaped how the growth factor moved through the tissue (PMID 12801514).
• Circulating carrier complexes: work on IGFBP-3 ternary complex regulation in feline diabetes mellitus reported disease-associated differences in the complex that carries IGF-I in blood (PMID 10856879), which is the main determinant of circulating growth-factor residence time.
• Transdermal protein delivery: a 2022 paper reported that a hydrophobic peptide, MTD 1067, enabled transdermal delivery of functional protein cargoes in the systems tested (PMID 35760980), which is general delivery science rather than a study of IGF-Des itself.
• Detectability: the antidoping method paper reported that immunopurification coupled to high-resolution mass spectrometry could detect Des(1-3)-IGF-I and related analogues (PMID 33587816), implying measurable persistence in the sample matrix studied.

Limits of the evidence for Module 5: none of these papers reports a half-life, bioavailability figure or volume of distribution for des(1-3)IGF-I in humans. Transport findings for intact IGF-I cannot be assumed to transfer to a truncated analogue with altered binding-protein interaction, and delivery studies using unrelated protein cargoes say nothing about this molecule specifically.

Module 6: Regulatory Status

Stated factually: des(1-3)IGF-I is not an approved medicine in the United States or the European Union. Recombinant human IGF-1 exists as an approved product in the form of mecasermin for defined paediatric growth-failure indications, but that approval covers the full-length recombinant protein, not a truncated analogue. Material sold as IGF-Des is supplied under research-use-only labelling, which by definition excludes human or veterinary administration and carries no assurance of pharmaceutical-grade identity, purity or sterility.

Compounding pharmacies in the United States operate under narrow statutory conditions: a bulk drug substance generally must be a component of an FDA-approved drug, appear on the relevant bulk drug substances list, or be the subject of an applicable USP monograph. A truncated IGF-I analogue does not sit in those categories, which is why it is not encountered as a compounded preparation.

In sport, the analogue is treated as a detectable target: researchers developed and validated an immunopurification and high-resolution mass spectrometry approach explicitly for antidoping detection of LongR³-IGF-I, Des(1-3)-IGF-I and R³-IGF-I (PMID 33587816). This section describes regulatory frameworks in general terms and is not legal advice; rules differ by country and change over time.

Limits of the evidence for Module 6: regulatory classification reflects approval and enforcement decisions, not a scientific verdict on a molecule. The absence of approval means no regulator has reviewed manufacturing, labelling or safety data for this analogue in humans.

What the Studies Did Not Test

Reading the six modules together, the gaps are as large as the findings. The verified literature did not include:

1. Human efficacy trials. No randomised or controlled human study of des(1-3)IGF-I appears in this set; the muscle-relevant data are in vitro promoter and myotube responses (PMID 33614996).
2. Dose-ranging or duration studies in people. No verified paper established an exposure range, schedule or ceiling in humans.
3. Long-term safety follow-up. The tumour-acceleration finding was reported in transgenic mice with mutant p53 (PMID 10702797), and no study tracked cancer incidence, glucose regulation or endocrine axis recovery after exposure in humans.
4. Head-to-head comparison with intact IGF-I. Binding-protein modulation was studied in retinal endothelial cells (PMID 11691647) and in the feline IGFBP-3 ternary complex (PMID 10856879), but not as a clinical comparison.
5. Route-specific pharmacokinetics. Transport work covered the blood–brain barrier (PMID 11025411) and cartilage (PMID 12801514) for IGF-I, not systemic kinetics for the truncated analogue.
6. Product quality. No verified study assessed the identity or purity of research-grade material as it is distributed.

The honest summary is that IGF-Des is a well-defined laboratory tool with a documented signalling profile, a documented proliferative hazard in at least two model systems, and essentially no human clinical evidence base. Anyone seeking to interpret this literature for a personal health question should do so with a licensed physician.

References

• Interactions of IGF-1 with the blood-brain barrier in vivo and in situ (Neuroendocrinology, 2000)
• Detection of LongR(3)-IGF-I, Des(1-3)-IGF-I, and R(3)-IGF-I using immunopurification and high resolution mass spectrometry for antidoping purposes (Drug Testing and Analysis, 2021)
• Efficient transdermal delivery of functional protein cargoes by a hydrophobic peptide MTD 1067 (Scientific Reports, 2022)
• IGFBPs modulate IGF-I- and high glucose-controlled growth of human retinal endothelial cells (The Journal of Endocrinology, 2001)
• Transport and binding of insulin-like growth factor I through articular cartilage (Archives of Biochemistry and Biophysics, 2003)
• Functional characterization of des-IGF-1 action at excitatory synapses in the CA1 region of rat hippocampus (Journal of Neurophysiology, 2005)
• Des (1-3) IGF-I-stimulated growth of human stromal BPH cells is inhibited by a vitamin D3 analogue (Molecular and Cellular Endocrinology, 2002)
• Des(1-3)IGF-1 treatment normalizes type 1 IGF receptor and phospho-Akt (Thr 308) immunoreactivity in predegenerative retina of diabetic rats (International Journal of Experimental Diabesity Research, 2003)
• Cooperative interaction between mutant p53 and des(1-3)IGF-I accelerates mammary tumorigenesis (Oncogene, 2000)
• Response of the porcine MYH4-promoter and MYH4-expressing myotubes to known anabolic and catabolic agents in vitro (Biochemistry and Biophysics Reports, 2021)
• Regulation of insulin-like growth factor-binding protein-3 ternary complex in feline diabetes mellitus (The Journal of Endocrinology, 2000)
• Characterization of pituitary IGF-I receptors: modulation of prolactin and growth hormone (American Journal of Physiology, 2002)