Several peptides studied in metabolic contexts — including BPC-157, GLP-1 analogues, and certain GH secretagogues — show effects on insulin sensitivity, but through different mechanisms and with very different evidence quality. Grouping them as 'peptides that improve insulin sensitivity' obscures more than it reveals.
What separates GLP-1 analogues from research peptides in the insulin sensitivity evidence?
GLP-1 receptor agonists (semaglutide, liraglutide) have large-scale RCT evidence for insulin sensitisation and are approved therapeutic agents. Research peptides like BPC-157 have animal data suggesting metabolic effects but no controlled human metabolic trials. These are not equivalent evidence bases and should not be cited in the same sentence without that distinction being explicit.
What is the metabolic tradeoff with GH secretagogues and insulin sensitivity?
GH secretagogues increase GH output, which has acute insulin-antagonising effects. Over longer cycles, improvements in body composition (reduced visceral fat) can secondarily improve insulin sensitivity. This creates a paradox: the mechanism that drives body composition improvement also transiently worsens glucose handling. This is well-documented in GH replacement literature and extrapolated to secretagogue use.