Follow-up: Retatrutide phase 2 in type 2 diabetes: the Lancet paper

Retatrutide phase 2 in type 2 diabetes: the Lancet paper Writing it up because I had to work it out twice and would rather nobody else did.

A follow-up question about Retatrutide phase 2 in type that I did not know to ask the first time.

The earlier thread answered what I asked. What I should have asked is below, and I think it is the one that matters.

This follows the opening post rather than contradicting it.

What we do not know about retatrutide, listed explicitly: long-term safety, real-world response rates, the dose response in diverse populations, whether the heart-rate signal persists or attenuates, durability of effect on withdrawal, efficacy in comorbidities beyond obesity.

I would rather post the uncertainty than round it away.

Whether triple agonism is additive or synergistic is an open question and the published work does not answer it. A phase 2 trial without a dual-agonist comparator arm cannot distinguish the two.

Discontinuation for adverse effects in phase 2 was not negligible at the higher doses. That figure belongs next to the efficacy figure whenever the efficacy figure is quoted.

The opening post and I disagree about the size of the effect, not about the direction.

Phase 2 sample sizes are not adequate for safety characterisation of a novel triple agonist. Phase 3 is where that question gets answered. Using phase 2 results to make claims about safety profile is using the trial for a purpose it was not designed for.

If the premise is wrong, everything after it is decoration.

How to read phase 2 without treating it as phase 3: phase 2 establishes that a dose range produces an effect and is tolerable enough to justify large trials. It does not establish safety, durability, or whether real humans differ from the selected population.

Correct me on the arithmetic if it is wrong; I would rather know.