It's what most of us that used them not for losing BW stated a long time ago.
It plateau because the body gets used to the side effect and so it's stop blunting the appetite etc.
I believe hope the glucose control continue to last because that's the only thing I care lol
If this were true, that they're like "diet pills" to which a tolerance develops and effects weaken, then you'd see weight regain over the long term on a maintainance dose. Based on 3 and 4 year extended trials, involving over 10,000 patients, that doesn't happen. Weight loss almost entirely happens in the first year, then maintained on the same dose for at least several more years (the limit of the trials).
You'd also expect the tolerance to fade after taking a break, and that doesn't happen either.
But these results are with pharma drugs, on a pharma protocol.
Plenty of anecdotal evidence that UGL users, particularly those who go off and back on repeatedly, develop increasingly weaker response, which lines up with the theory of immunogenicity development, "reexposure events" and of course all the unknown contaminants potentially contributing to its development.
When and if antibody tests become available at blood labs, something expected to become common for all protein based therapies in the future (so doctors can check patients who stop responding to various peptide drugs), it will be interesting to see how UGL users compare to those on pharma.