STEP 2: semaglutide for weight loss in adults with type 2 diabetes

Why this study matters

Many people living with obesity also have type 2 diabetes. Weight-loss medicines often work differently in this group, so a separate trial was needed. STEP 2 tested semaglutide (Wegovy, Ozempic) at the 2.4 mg weight-management dose in adults with type 2 diabetes. It also included a 1.0 mg dose, which is a dose used in diabetes treatment, so readers can see how the two doses behaved in the same trial. Canadian readers with diabetes who hear about semaglutide will want to know what this trial showed for people like them.

Who was in the study

The trial screened 1595 people and randomly assigned 1210 adults. Everyone had a body mass index (BMI) of at least 27. BMI is a number that compares weight with height. Everyone had type 2 diabetes for at least 180 days before screening, with an HbA1c between 7% and 10%. HbA1c is a blood test that shows average blood sugar over about three months. People were recruited from 149 outpatient clinics in 12 countries across Europe, North America, South America, the Middle East, South Africa and Asia. The trial lasted 68 weeks. The summary we reviewed does not report the age range.

What the researchers did

This was a randomized, double-blind, double-dummy trial. Randomized means chance decided who got which treatment. Double-blind means neither the participants nor the study staff knew who got what. Double-dummy means everyone received matching injections so the doses could not be told apart. A placebo is an injection with no active medicine.

Participants were split evenly into three groups: 404 received semaglutide 2.4 mg, 403 received semaglutide 1.0 mg, and 403 received placebo. All injections were given under the skin once a week for 68 weeks. All three groups also received a lifestyle intervention, which means support with diet and physical activity.

The main results compared semaglutide 2.4 mg with placebo on two measures at 68 weeks: the percentage change in body weight, and the share of people who lost at least 5% of their starting weight. The analysis was by intention to treat, which means people were counted in the group they were assigned to. Safety was assessed in everyone who received at least one dose.

What they found

At week 68, average body weight had changed by -9.6% with semaglutide 2.4 mg and by -3.4% with placebo (R32-C03). The difference was -6.2 percentage points, with a 95% confidence interval of -7.3 to -5.2. A confidence interval is the range in which the true difference is likely to sit. The whole range is below zero, so the benefit over placebo was clear.

More people on semaglutide 2.4 mg lost at least 5% of their starting weight: 68.8% (267 of 388) compared with 28.5% (107 of 376) on placebo. The odds ratio was 4.88 (95% CI 3.58 to 6.64). An odds ratio above 1 means the outcome was more likely in the semaglutide group.

The summary we reviewed does not report the weight change for the 1.0 mg group.

Side effects and people who stopped

Side effects of any kind were more common with the medicine than with placebo. They were reported by 87.6% of people on semaglutide 2.4 mg (353 of 403), 81.8% on semaglutide 1.0 mg (329 of 402), and 76.9% on placebo (309 of 402).

Gastrointestinal (stomach and bowel) events were mostly mild to moderate. They were reported by 63.5% of people on semaglutide 2.4 mg, 57.5% on semaglutide 1.0 mg, and 34.3% on placebo (R32-C04).

The summary we reviewed does not report how many people stopped treatment, or how many stopped because of side effects.

What this study does not tell you

• Our summary is based on the abstract and extracted data, not the full paper.
• This trial enrolled only adults with type 2 diabetes. Its results are not interchangeable with STEP 1, which enrolled people without diabetes. The two trials cannot be compared side by side.
• All three groups received lifestyle support, so the results show what semaglutide adds to that support.
• The trial did not compare semaglutide with any other weight-management medicine.
• The trial lasted 68 weeks and does not show what happens after treatment stops.
• The trial was funded by the company that makes semaglutide.

What it means in Canada

STEP 2 is the main trial of semaglutide 2.4 mg in people with type 2 diabetes and a higher body weight. The weight change with placebo (-3.4%) is a reminder that lifestyle support on its own also led to some weight loss in this group. For how the medicine is used in Canada, see semaglutide in Canada. For questions about what provincial plans pay for, see public drug coverage by province. To look at care options, see compare services.

Related reading

Other studies in this library that bear on the same question.

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