STRIDE is the first trial to show a GLP-1 receptor agonist improving how far someone with blocked leg arteries can walk, and the result is being carried into weight-loss marketing as evidence that semaglutide “improves circulation.” What the trial measured is narrower and more interesting than that: a ratio on a treadmill, over one year, at the diabetes dose, in people who were mostly not obese. The kidney counterpart to this trial is covered in the FLOW article; this page is about the legs.
What was run
STRIDE was a double-blind, randomized, placebo-controlled phase 3b trial at 112 outpatient sites in 20 countries. Eligible participants were aged 18 or older with type 2 diabetes and peripheral artery disease causing intermittent claudication — Fontaine stage IIa, meaning they could still walk more than 200 meters — plus an ankle-brachial index of 0.90 or below or a toe-brachial index of 0.70 or below. Of 1,363 patients screened, 792 were randomized 1:1 to subcutaneous semaglutide 1.0 mg once weekly or placebo for 52 weeks. 195 (25%) were female and 597 (75%) male, and median age was 68 years (IQR 61 to 73).[1]
The trial’s design paper describes the cohort further: 25.6% were current smokers, 87.9% had hypertension, 42.7% had coronary heart disease, mean body-mass index was 29.6, mean glycated hemoglobin was 7.3% and median diabetes duration 12 years. Median maximum walking distance at baseline was 186 meters on a constant-load treadmill.[5] That last figure is the denominator everything else has to be read against.
The endpoint is a ratio, and both arms improved
The primary endpoint was the ratio to baseline of maximum walking distance at week 52. The estimated median ratio was 1.21 (IQR 0.95 to 1.55) on semaglutide against 1.08 (IQR 0.86 to 1.36) on placebo, giving an estimated treatment ratio of 1.13 (95% CI, 1.06 to 1.21; P = 0.0004).[1]
Three things follow from the way that is built. The placebo group walked 8% further too, which is what a year of trial-supervised attention does on its own. The 13% is the margin above that, not the total improvement. And on a median baseline of 186 meters, a 13% relative gain is roughly 24 meters — about the length of a supermarket aisle.
The interquartile ranges carry the part no summary mentions. The 25th percentile of the ratio was below 1 in both arms — 0.95 on semaglutide and 0.86 on placebo — so more than a quarter of participants in each group walked a shorter distance at week 52 than they had at baseline.[1] A median improvement and a universal improvement are different claims, and this trial supports only the first.
The secondary endpoints, and the week the drug stopped
Pain-free walking distance moved on the same scale: median ratio 1.21 (IQR 0.92 to 1.52) against 1.10 (IQR 0.86 to 1.44), estimated treatment ratio 1.11 (95% CI, 1.033 to 1.197; P = 0.0046). Disease-specific quality of life on the VascuQoL-6 improved by a median of 2.0 points against 1.0, a Hodges-Lehmann estimate of 1.00 point (95% CI, 0.478 to 1.518; P = 0.0108). The Walking Impairment Questionnaire global score rose 9.48 points against 6.51, and the SF-36 physical functioning domain 2.98 against 1.52, neither with a confidence interval posted.[2]
The most useful secondary endpoint is the one measured after treatment ended. At week 57, five weeks past the final injection, the median ratio was 1.16 against 1.10 and the estimated treatment ratio had fallen to 1.08 (95% CI, 1.004 to 1.156; P = 0.0380).[2] The lower bound is four thousandths above 1. In five weeks, most of the separation between the arms was gone, which is consistent with everything else known about what happens when these drugs stop — the subject of the tapering article.
Where the obvious explanation fails
The intuitive reading is that walking improved because participants weighed less and their blood sugar was better controlled. Body weight fell 5.2 kg (SD 4.8) on semaglutide against 1.2 kg (SD 4.2) on placebo, and glycated hemoglobin fell 0.8 percentage points (SD 1.1) against a rise of 0.2 (SD 1.1).[2] Both moved in the expected direction.
The trial’s own subgroup analysis does not support the explanation. Across a cohort with a median glycated hemoglobin of 7.1% and a median body-mass index of 28.7, the treatment ratio for maximum walking distance was 1.15 against 1.13 for diabetes duration under and over 10 years (P = 0.80), 1.12 against 1.16 for body-mass index under and over 30 (P = 0.58), and 1.13 in both glycated hemoglobin strata, under and over 7% (P = 0.99). Pain-free walking distance was likewise consistent, with interaction P values above 0.1 throughout, and the authors report that reduction in body-mass index correlated only weakly with the walking improvement.[3]
So the benefit was as large in people who were not obese as in people who were, and as large in people whose diabetes was already well controlled as in people whose was not. That is the opposite of what a weight-mediated mechanism predicts, and it is the reason the trial’s own investigators describe the mechanism as an open question. It also means the result cannot be borrowed for the claim it is most often borrowed for: that losing weight on a GLP-1 is what improves the legs.
A post hoc analysis by sex found the same flatness. Of the 792 participants, 195 (24.6%) were female and 597 (75.4%) male, with geometric mean baseline walking distances of 187.3 and 191.5 meters. Improvement favored semaglutide in both groups at week 52 (P for interaction = 0.65), at week 57 (P = 0.53) and on pain-free walking distance (P = 0.80), while the women enrolled were younger, smoked less, and less often had coronary artery disease, heart failure or antiplatelet prescriptions than the men.[4]
What 24 meters is worth
There is a comparator for a walking gain, and it is not a drug. Supervised treadmill exercise is guideline-recommended first-line therapy for claudication, and a randomized trial of it in 210 people with peripheral artery disease reported improvement in six-minute walk distance against non-exercise controls of 13.0 meters at six weeks (P = 0.049), 31.8 meters at twelve weeks (P < 0.001) and 33.9 meters at 26 weeks (P < 0.001).[6]
Those are not the same measurement — a six-minute walk test and a constant-load treadmill test are different instruments, and the populations differ — so the two numbers cannot be subtracted from one another. What the comparison establishes is scale: a structured exercise program moves walking distance by a comparable order of magnitude, over three months rather than twelve. Notably, the same trial found its patient-reported walking benefit had disappeared by 26 weeks even as the objective gain held, which is a reminder that measured distance and felt capacity are not the same endpoint. What is known about combining exercise with a GLP-1 is set out in the exercise article.
What STRIDE did not measure
No limb outcome. There is no amputation endpoint, no revascularization endpoint, no critical-limb-ischemia endpoint and no mortality endpoint in the trial’s registered outcome list — the endpoints are walking distance, quality of life and cardiometabolic measurements.[2] A trial showing that people walk further has not shown that fewer of them lose a leg. The cardiovascular outcome evidence for this molecule is a separate body of work, covered in the SELECT article.
No one without type 2 diabetes. Every participant had it, and the authors state the need for future studies to assess efficacy and safety in people with peripheral artery disease who do not.[1] No one with severe disease either: eligibility required the ability to walk more than 200 meters, which excludes the people whose claudication is worst.
And the retention columns run against the drug. Of the 396 assigned semaglutide, 30 did not complete against 17 of 396 on placebo — 18 against 12 withdrawing themselves, 8 against 5 lost to follow-up, and 4 against 0 stopped by physician decision. Nausea was recorded in 22 of 396 on semaglutide against 3 of 395 on placebo. Serious adverse events were similar, 74 against 78, and deaths were 4 against 9.[2] The published abstract reports six treatment-related serious adverse events in five participants (1%) on semaglutide and nine in six (2%) on placebo, with no treatment-related deaths.[1] Deaths were not an endpoint, the trial was not powered to compare them, and 13 events cannot support any inference.
What was in the injection
Every figure here belongs to branded, FDA-approved semaglutide at 1.0 mg weekly — the diabetes dose, not the 2.4 mg used for weight management — supplied free, on top of the statins, antiplatelets and antihypertensives this population was already taking. Sellers listed on the semaglutide board largely dispense compounded preparations, which are not FDA-approved and are not reviewed by the FDA for safety, efficacy or quality before they are dispensed.
The honest summary is short. In people who already have type 2 diabetes and symptomatic claudication, a year of semaglutide 1.0 mg added about 13% to how far they could walk before stopping, independent of how much weight or blood sugar they lost, and most of that margin was gone five weeks after the last injection. That is a real and unusual finding. It is not a circulation claim, not a limb-salvage claim, and not a reason anybody without peripheral artery disease should read anything into it.