My friend who is a biochemist in China sent me the below paper on how they make Semaglutide in his lab. Semaglutide is a newly discovered, long acting GLP-1 RA with 94% homology to natural GLP-1. Semaglutide was obtained through modifying three amino acid residues of natural GLP-1 (Ala8 altered to Aib, Lys34 altered to Arg, and a side chain introduced to Lys26, respectively). Previously, the synthetic routes of semaglutide are all based on solid-phase peptide synthesis (SPPS), which leads to high production costs. The Chinese figured out a way to make the same formula yet keeping the price down so it is affordable, plus being able to produce more product.
More of my cut and paste skills:
....we applied a newly developed soluble hydrophobic-support-assisted liquid-phase synthetic method to the total synthesis of semaglutide and established a simple and efficient route for the total synthesis of semaglutide through elaborate optimizations of the reaction conditions and innovation of the post-synthesis treatment method
Things have changed since 2005 when Semaglutide had not been sent to market.