---
title: "STEP 3: Semaglutide Phase 3 Results | Primara Labs"
url: https://www.primaralabs.com/research/trials/step-3
source: Primara Labs, markdown mirror of the HTML page
---

# STEP 3

In STEP 3, a phase 3 trial of semaglutide in US adults without diabetes with overweight (BMI 27 or greater) plus at least 1 comorbidity or obesity (BMI 30 or greater) (n=611), mean body weight fell 16.0% on 2.4 mg over 68 weeks, against 5.7% on placebo (treatment-policy estimand; Wadden TA et al. JAMA 2021 (STEP 3)).

Primara Labs sells some of the compounds covered here. Every figure on this page links to its source and the date it was checked.

Updated 24 September 2026

Semaglutide Explained: STEP, SUSTAIN and SELECT Trials (Philippines)2:07·[Transcript and chapters](https://www.primaralabs.com/videos/semaglutide)

## Results

Mean percent change in body weight by arm, as each source reports it. Navy bars are the trial arms, grey bars the comparator. Bars from different trials are not a head-to-head comparison: populations, durations and estimands differ.

## Side effects reported

In STEP 3, discontinuation because of adverse events was 5.9% on 2.4 mg, against 2.9% on placebo. The most frequently reported adverse events were gastrointestinal adverse events in 82.8% on 2.4 mg against 63.2% on placebo, nausea in 58.2% on 2.4 mg against 22.1% on placebo, constipation in 36.9% on 2.4 mg against 24.5% on placebo and diarrhoea in 36.1% on 2.4 mg against 22.1% on placebo.

| Event | 2.4 mg | Placebo |
| --- | --- | --- |
| Discontinuation for adverse events | 5.9% | 2.9% |
| Gastrointestinal adverse events | 82.8% | 63.2% |
| Nausea | 58.2% | 22.1% |
| Constipation | 36.9% | 24.5% |
| Diarrhoea | 36.1% | 22.1% |
| Vomiting | 27.3% | 10.8% |

Design

## Trial design and sources

Compound

Semaglutide

Phase

3

Population

US adults without diabetes with overweight (BMI 27 or greater) plus at least 1 comorbidity or obesity (BMI 30 or greater)

Participants randomised

611

Duration

68 weeks

Primary endpoint

Co-primary: percentage change in body weight and loss of 5% or more of baseline weight by week 68

Estimand

treatment-policy

Read out

1 April 2021

Discontinuation for adverse events is 5.9% against 2.9% in the safety section; the disposition paragraph gives 6.4% against 2.9%.

-   Wadden TA et al. JAMA 2021 (STEP 3) [open](https://doi.org/10.1001/jama.2021.1831) · checked 23 September 2026
-   ClinicalTrials.gov NCT03611582 [open](https://clinicaltrials.gov/study/NCT03611582) · checked 23 September 2026
-   Registry: NCT03611582

Questions

## STEP 3, answered

### What did STEP 3 find?

In STEP 3, a phase 3 trial of semaglutide in US adults without diabetes with overweight (BMI 27 or greater) plus at least 1 comorbidity or obesity (BMI 30 or greater) (n=611), mean body weight fell 16.0% on 2.4 mg over 68 weeks, against 5.7% on placebo (treatment-policy estimand; Wadden TA et al. JAMA 2021 (STEP 3)).

### What side effects were reported in STEP 3?

In STEP 3, discontinuation because of adverse events was 5.9% on 2.4 mg, against 2.9% on placebo. The most frequently reported adverse events were gastrointestinal adverse events in 82.8% on 2.4 mg against 63.2% on placebo, nausea in 58.2% on 2.4 mg against 22.1% on placebo, constipation in 36.9% on 2.4 mg against 24.5% on placebo and diarrhoea in 36.1% on 2.4 mg against 22.1% on placebo.

Related

## More on semaglutide

-   [STEP 1](https://www.primaralabs.com/research/trials/step-1)
-   [STEP 2](https://www.primaralabs.com/research/trials/step-2)
-   [STEP 4](https://www.primaralabs.com/research/trials/step-4)
-   [STEP 5](https://www.primaralabs.com/research/trials/step-5)
-   [STEP 8](https://www.primaralabs.com/research/trials/step-8)
-   [SELECT](https://www.primaralabs.com/research/trials/select)
-   [SURMOUNT-5](https://www.primaralabs.com/research/trials/surmount-5)
-   [Evidence Map: Semaglutide](https://www.primaralabs.com/research/evidence#semaglutide)
-   [Semaglutide 15mg](https://www.primaralabs.com/marketplace/semaglutide-15mg)