THE TRIAL LEDGER
Semaglutide vs tirzepatide: what the head-to-head trial actually measured
-13.7% against -20.2% over 72 weeks in SURMOUNT-5 — and a 20% cut in cardiovascular events in 17,604 people. A data-forward reading of the trial record, every figure traced to its study.
The short version
Semaglutide is a once-weekly (or once-daily pill) medicine that copies a natural gut hormone called GLP-1, which tells your brain you are full and your pancreas to handle sugar. It is FDA-approved for type 2 diabetes, long-term weight management, lowering heart-attack and stroke risk in people with heart disease, and a fatty-liver condition called MASH. In the big STEP 1 study, people lost about 15% of their body weight over roughly 16 months [2]. In a 2025 face-off called SURMOUNT-5, the newer drug tirzepatide beat it on the scale — about 20% lost versus 14% [1]. But semaglutide has its own deep record: it cut serious heart events by 20% in a 17,604-person trial [3]. What people report — including the downsides like nausea and "sulfur burps" — is on the effects page. This site reads the numbers and cites every one. It is a digest, not a clinic, and it offers no doses or prescriptions.
The head-to-head result, stated plainly
In SURMOUNT-5, the first large head-to-head trial of the two leading incretin drugs, 751 adults with obesity were randomized to semaglutide or tirzepatide for 72 weeks. Tirzepatide produced a mean weight change of -20.2% versus -13.7% for semaglutide — a ~6.5 percentage-point gap, statistically significant at P<0.001 [1].
That is the headline, and it is worth saying without softening: on body weight, in a direct comparison, tirzepatide won. The same pattern held in type 2 diabetes a year earlier. In SURPASS-2, tirzepatide produced greater reductions in both HbA1c (a three-month blood-sugar average) and body weight than once-weekly semaglutide 1.0 mg [9].
The full breakdown — every comparable figure, side by side — lives on the semaglutide vs tirzepatide page. What follows here is the rest of the ledger, because weight on the scale is one column, not the whole accounting.
Where semaglutide's numbers are strongest
Cardiovascular outcomes are semaglutide's deepest evidence. In SELECT (n=17,604) — adults with established cardiovascular disease and overweight or obesity but no diabetes — once-weekly semaglutide 2.4 mg cut the composite of cardiovascular death, nonfatal heart attack and nonfatal stroke by 20% versus placebo (HR 0.80; 95% CI 0.72-0.90; P<0.001) [3]. That is a hard-endpoint outcome trial, not a weight number, and tirzepatide does not yet have a published equivalent.
The diabetes outcome trial came first. In SUSTAIN-6, semaglutide reduced the same three-point cardiovascular composite by 26% (HR 0.74; 95% CI 0.58-0.95) in people with type 2 diabetes at high risk [4]. And in FLOW (n=3,533), once-weekly 1.0 mg reduced major kidney-disease events — kidney failure, a ≥50% drop in kidney function, or kidney/cardiovascular death — by 24% (HR 0.76; 95% CI 0.66-0.88) [5].
Read together, the ledger reads like this: tirzepatide leads on weight, semaglutide leads on the depth and breadth of its outcome evidence. Both statements are true at once.
What is semaglutide, structurally
Semaglutide is a 31-amino-acid peptide — a short protein chain — engineered as a long-acting copy of human GLP-1 (glucagon-like peptide-1), the gut hormone released after a meal that signals fullness and helps control blood sugar [27]. Native GLP-1 lasts about two minutes in the body. Two design changes fix that: a swapped amino acid at position 8 blocks the enzyme DPP-4 that would chew it up, and a fatty-acid "tail" makes it stick to albumin, the most abundant protein in blood, so it clears slowly. The result is a roughly one-week half-life — the structural reason a single weekly injection works [27].
Its molecular formula is C187H291N45O59 (molecular weight ~4,114 Da; CAS 910463-68-2). It comes two ways: a once-weekly shot under the skin, and a once-daily tablet paired with an absorption helper called SNAC [17]. The Semaglutide research page traces the mechanism in full, and the Semaglutide effects page covers what people report and the cited safety cautions.
What this digest is — and is not
This is an editorial digest: a data-forward reading of the published semaglutide trial record, led by the head-to-head comparison against tirzepatide. Semaglutide is a real, FDA-approved medicine, and the content here summarizes peer-reviewed studies and approved-label facts. It is not medical advice, and it recommends no doses for any individual.
The word "telehealth" in the domain is editorial framing for an availability-focused reading of the record — not a service. There is no clinic here, no prescriber, and nothing is sold. Every dose figure on this site appears as a study-design or labeling fact, in the third person, never as guidance. Browse the Semaglutide references for the full source list.