One measurement, two answers, and the comparison decides which one you get. In a 32-week trial of 120 people with type 2 diabetes, blood-vessel responsiveness rose 0.11 against each participant’s own baseline, 95% CI 0.008 to 0.21, p=0.03 [1]. Against the placebo group the estimate was the same 0.11, with a 95% CI of −0.04 to 0.24 and p=0.16. Four adhesion molecules were measured and they did not move together, with one rising against placebo. The marker in this family that does move reliably is inflammation: hsCRP fell 37.8% at 104 weeks in SELECT [2].
Two sentences can describe one measurement. “Semaglutide improved blood vessel function, p=0.03.” And: “Semaglutide did not significantly improve blood vessel function versus placebo, p=0.16.” Both are accurate descriptions of the same number in the same study, and the difference between them is the entire subject of choosing what to compare against.
The study
A post hoc analysis of a 32-week randomized trial that had been designed to look at cardio-renal organ damage. One hundred and twenty participants with type 2 diabetes, aged 50 or over, were randomized to semaglutide, empagliflozin, both together, or placebo. [1] The analysis looked at a measure of how well blood vessels widen in response to demand, and at four adhesion molecules the endothelium releases.
The same estimate, twice
In the semaglutide group the vessel-response index rose 0.11 from each participant’s own starting value, with a 95% confidence interval of 0.008 to 0.21 and p=0.03. Compared with the placebo group it also rose 0.11 — with a confidence interval of −0.04 to 0.24 and p=0.16.
Nothing about the measurement changed. What changed is what it was held up against. People in a trial tend to improve for reasons that have nothing to do with the drug: closer monitoring, changed habits, regression to the mean, the season. A placebo group exists to absorb all of that, and when you subtract it the effect here stopped being distinguishable from noise.
The markers disagreed with each other
Four adhesion molecules were measured and they did not move together. E-Selectin fell against placebo, by 9 in both the semaglutide group, 95% CI −14.1 to −5.1, and the combination group, 95% CI −14.3 to −5.2, both at p<0.01. That is the direction usually read as healthier.
VCAM-1 went the other way. It rose against placebo, by 12.3 in the semaglutide group, 95% CI 2.8 to 20.8, p=0.01, and by 16.2 in the combination group, 95% CI 7.2 to 24.3, p<0.01. P-Selectin and ICAM-1 did not move significantly in any group. The authors describe the responses as heterogeneous and suggest the molecules play distinct roles, which is an honest way of saying nobody knows what the pattern means.
Note what a selective summary could do with that. Quote E-Selectin, omit VCAM-1, and this becomes a study showing improved endothelial health. It is the same move a composite endpoint makes structurally, performed by hand.
The marker that does move, and one that moved too much
Inflammation is the comparison worth having beside this one. A prespecified SELECT substudy reported high-sensitivity CRP down 37.8% at 104 weeks against placebo [2]. The reduction was evident by weeks 4 and 8, and it appeared among participants who did not lose weight. That is a placebo comparison in a trial of 17,604 people, and its authors still describe reduced inflammation as contributing “in part” rather than as the mechanism. The reading is in the hsCRP substudy.
A third study shows what happens when the comparison is right and the result is still too large. A matched cohort of 4,153 patients per arm compared these drugs against mineralocorticoid receptor antagonists as fourth-line therapy in resistant hypertension [3]. Blood pressure fell by a similar amount in both arms, −5.7 mmHg against −6.3 mmHg at 12 weeks, while all-cause mortality came in at a hazard ratio of 0.34. A two-thirds reduction in death with the treated quantity equalized is a confounding signature, set out in same blood pressure, different outcomes.
Why any of this matters to a reader
Not because endothelial biomarkers should influence a purchase. They should not — these are laboratory measures in 120 people, not events in anybody.
It matters because “improved from baseline” is everywhere. It appears in clinic testimonials, in single-arm studies, in before-and-after marketing, and in summaries of real trials that had a placebo group available and quoted the baseline comparison anyway. Once you notice the phrase you cannot stop seeing it, and it is the same weakness that makes an uncontrolled study unable to show what it appears to show.
The test is one question: compared to what? If the answer is “to how they were before,” you have been told how a group of people changed over time, not what the drug did. Almost nothing a seller publishes survives that question, which the disclosure scorecard measures from the other direction.