Same molecule. Longer leash. IGF 1 LR3 is a long arginine 3 analog of insulin like growth factor 1. The Arg3 substitution prevents binding to IGFBP 3, the carrier protein that normally clears IGF 1 from circulation. Half life Human insulin IGF 1 and familial longevity at middle age Aging Ipamorelin Side Effects: What to Expect Nulevel Wellness Medspa Late life targeting of the IGF 1 receptor improves healthspan and lifespan in female mice Nature Communications Recombinant expression of IGF 1 and LR3 IGF 1 fused with xylanase in Pichia pastoris Applied Microbiology and Biotechnology Springer Nature Link