Everything known about these drugs comes from people whose kidneys work well enough to be in a trial. This is what the evidence looks like for people whose kidneys have failed, and the shape of it is the point.
Who is missing from the trials
The large cardiovascular and weight-loss trials exclude end-stage kidney disease, and the kidney trial that made news enrolled people with chronic kidney disease rather than people on dialysis — a distinction the coverage rarely draws. So a patient on dialysis, who may need to lose weight to qualify for a transplant, is asking a question no randomized trial has answered.
This review gathered what exists: 19 studies, 388 patients, 91.5% on renal replacement therapy. [1] Semaglutide accounted for 266 of them, liraglutide 66, dulaglutide 47, and tirzepatide nine. Nine patients, in the world literature.
What it found
On semaglutide, weight fell 3.09 kg at three months, 95% CI −5.95 to −0.24; 3.68 kg at six months, 95% CI −5.71 to −1.65; and 7.00 kg at twelve months, 95% CI −11.38 to −2.61 with heterogeneity of 79.2%. Glycated hemoglobin fell 0.75 percentage points at twelve months, 95% CI −1.07 to −0.43.
Some estimates did not exclude no effect: BMI at three months, 95% CI −2.92 to 0.09, and HbA1c at six months, 95% CI −1.20 to 0.20. Both liraglutide weight estimates crossed zero as well — 95% CI −7.73 to 3.26 at three months and −11.26 to 2.27 at six.
The estimates that are usable
Not all of it is like that. Any gastrointestinal event came in at 39%, 95% CI 25% to 55%, and discontinuation because of side effects at 9%, 95% CI 4% to 20%. Those are wide but they say something: side effects are common in this population and roughly one person in eleven stopped because of them.
The twelve-month weight figure is similar — a real effect with an interval running from about two and a half to eleven kilograms, and heterogeneity high enough that the studies disagreed substantially. It is enough to say the drug does something and not enough to say how much, which a high heterogeneity statistic always implies.
What the authors conclude
That semaglutide may be considered in end-stage kidney disease, that the results are primarily hypothesis-generating, and that prospective randomized trials are urgently needed. All three clauses belong together. A drug can be reasonable to try in a population where nothing else works while the evidence for it remains this thin.
Why it belongs on a site about buying
Because nobody on this roster screens for kidney failure, and a person on dialysis filling out a telehealth intake form is in a category the whole evidence base excludes. Dosing, clearance and hypoglycemia risk are all different when kidneys have stopped working, and none of that is a question an online questionnaire is built to catch — the census of what goes unasked counts how much.
More generally, this is the clearest example available of what the gap between trial populations and real ones actually costs. Exclusion criteria are written to protect a trial’s result. They also decide, years later, which patients have evidence and which have nineteen small studies.