Almost every figure on this site describes a month. This one describes three and a half years, which is the horizon that actually decides what a GLP-1 costs. SURMOUNT-1 randomized 2,539 people with obesity, of whom 1,032 also had prediabetes, to tirzepatide at 5, 10 or 15 mg or to placebo, and followed the prediabetes group for 176 weeks of treatment plus 17 weeks off it [1]. Set beside what this market charges, it is the closest thing to a return on the money that exists.
What held
At 176 weeks the mean change in body weight was −12.3 per cent at 5 mg, −18.7 per cent at 10 mg and −19.7 per cent at 15 mg, against −1.3 per cent on placebo (P < 0.001 for all). That is not a 72-week headline extrapolated — it is the measurement at three and a third years.
Type 2 diabetes was diagnosed in 1.3 per cent of tirzepatide participants against 13.3 per cent on placebo, a hazard ratio of 0.07 (95% CI 0.0 to 0.1). In a prediabetes population that is the outcome the whole intervention is for.
What that means for the bill
A prevention effect that depends on continued treatment is a recurring cost, not a one-time one. Tirzepatide’s median published figure across the sellers tracked here is $249 a month, and the range runs 6.6 times from $75 to $497 — so the same three and a half years costs very different amounts depending on which page a reader lands on — a spread the ranked board lays out seller by seller.
Two things follow for anyone buying. The dose matters to the result: 10 and 15 mg produced substantially more weight loss than 5 mg, and most sellers publish nothing about what a higher dose costs. And a three-year horizon makes the difference between an advertised figure and a billed one compound into real money, which is why the gap between the two is worth establishing before the first charge rather than the thirtieth.
What the trial does not answer
Seventeen weeks is a short look at stopping, and the trial was not designed to describe what happens over years without the drug. It also says nothing about people without prediabetes, who were the larger part of SURMOUNT-1 and not the subject of this analysis. Gastrointestinal events were the most common adverse events, mostly mild to moderate and concentrated in the first 20 weeks of dose escalation, and no new safety signals were identified.
Price figures are computed from this site’s own records at build time, most recently read September 2026, across 456 priced sellers. The trial figures are cited.