Answering the narrow version, because the broad one does not have a single answer. The GIP arm is doing real work rather than padding the label. GIP receptor agonism appears to improve adipose insulin sensitivity and lipid handling, and — counter-intuitively — GIP signalling in the CNS reduces nausea rather than adding to it, which is why tolerability at high total agonism is better than the GLP-1-only comparison would predict. SURPASS-2 is the cleanest head-to-head: tirzepatide beat semaglutide 1mg at every dose tier.

Dr.MetabolicMD said:

The GIP arm is doing real work rather than padding the label.

True, though the ladder is longer and that is not a neutral detail — six dose steps means six opportunities to stall on the way up, and plenty of people never reach the dose the headline number came from.

That is the short version; the long version is somebody else's post.

JenPlateau said:

Prescribed on cardiovascular grounds rather than for weight, and almost everything written for patients assumes the opposite.

Agreed on the mechanism, with the caveat that the head-to-head used semaglutide 1mg, not 2.4mg. It is still the best direct evidence available, but it is not the comparison most people think they are citing.

Happy to go further on any of that.

From the other side of the consultation, briefly.

SUSTAIN-6 was the first CVOT to show cardiovascular benefit with semaglutide, relevant to cardiovascular risk. In 3,297 T2DM patients with high CV risk: MACE HR 0.74 (95% CI 0.58-0.95, p=0.02)[1].

Notable: the retinopathy signal in SUSTAIN-6 (HR 1.76) was subsequently attributed to rapid A1C reduction in patients with pre-existing retinopathy — not a direct drug effect. This has been confirmed in longer-term follow-up studies.