IGF-1 DES is insulin-like growth factor 1 with its first three amino acids clipped off the N-terminus. Where native IGF-1 is 70 residues, this variant is 67, missing the opening glycine-proline-glutamate (Gly-Pro-Glu) tripeptide. The short name is shorthand for des(1-3)IGF-1. It carries CAS number 112603-35-7 and the molecular formula C319H501N91O96S7, with a mass around 7,371 g/mol (Wikipedia summary of des(1-3)IGF-1IGF-1)).
Unlike many lab peptides, this one occurs in nature. It was first isolated from bovine colostrum and human brain in the mid-1980s, and later from porcine uterus, and it appears to arise from cleavage of normal IGF-1 rather than from a separate gene (review in *Cytokine & Growth Factor Reviews*, Carlsson-Skwirut and colleagues, 1996).
Why the missing three residues matter
IGF-1 normally circulates bound to a family of IGF-binding proteins (IGFBPs), which hold it in reserve and limit how much reaches the receptor. The N-terminal Gly-Pro-Glu region sits in the part of IGF-1 that contacts those binding proteins. Remove it, and binding to the IGFBPs drops sharply. Published work reports roughly 25-fold weaker binding to IGFBP-3, the dominant carrier, with the glutamate at position 3 doing much of that work.
Less sequestration means more free peptide available to the IGF-1 receptor. In cultured cells, des(1-3)IGF-1 is generally about 10-fold more potent than native IGF-1 at driving proliferation and hypertrophy. The receptor affinity itself is similar to IGF-1's; the potency gain is mostly about escaping the binding proteins (Wikipedia summaryIGF-1)).
One more wrinkle: the tripeptide that gets cleaved off, Gly-Pro-Glu (GPE), turned out to have its own activity in neural injury models, studied separately from the parent molecule.
State of the evidence
The mechanistic and animal literature is real but narrow. Studies have characterized its potency in cell culture and looked at effects on neuronal markers and IGF-1 receptor signaling, where it and native IGF-1 reach similar endpoints through partly different cellular routes (Corvino et al., *Neuroscience Letters*, 2012, PubMed-indexed). Animal work has examined growth and muscle endpoints.
What does not exist is a meaningful human clinical record. There is no completed program establishing safety or efficacy in people, and no formal toxicology dataset covering things like genotoxicity, carcinogenicity, or reproductive effects. IGF-1 DES is not an approved drug anywhere and is sold only as a research chemical. Nothing here is medical or dosing advice, and the compound is not intended for human consumption.
Regulatory and anti-doping status
For athletes, the line is clear. The World Anti-Doping Agency bans exogenous IGF-1 and its analogues, including the DES variant, under category S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics), prohibited at all times, in and out of competition. Anti-doping bodies treat all forms of exogenous IGF-1 as prohibited (USADA on IGF-1 and the Prohibited List).
The buyer's angle: identity and purity
Because this is a research chemical and not a regulated pharmaceutical, there is no official manufacturing standard behind a vial. A 67-residue peptide is also easy to confuse on a label with the more common full-length IGF-1 or the longer-acting IGF-1 LR3, which is a different molecule entirely. If you are evaluating sellers, the facts that matter are third-party identity and purity testing: a recent certificate of analysis from an independent lab (mass spectrometry to confirm the molecule, HPLC for purity), tied to the specific batch. peptideone aggregates published vendor test results and reputation signals so those quality claims can be compared rather than taken on trust.
Summary: des(1-3)IGF-1 is a genuine, naturally occurring IGF-1 variant with a documented mechanism and real preclinical data, but essentially no human evidence, no approval, and a clear WADA ban.