Liraglutide for teens with obesity: what a 56-week trial found

Why this study matters

Obesity in adolescents is a long-term condition, and lifestyle support alone does not work well for everyone. This trial was one of the first large randomized tests of a GLP-1 medicine in people under 18. It matters for Canadian families because it shows what the medicine did for growing teenagers, how their bodies responded once the medicine was stopped, and what side effects appeared.

Who was in the study

The trial enrolled 251 adolescents aged 12 to under 18 years who had obesity and had not responded well to lifestyle therapy alone. 125 were assigned to liraglutide and 126 to placebo. The trial had a 56-week treatment period followed by a 26-week follow-up period without treatment. The summary we reviewed does not report whether any participants had diabetes, or where the trial was run.

What the researchers did

This was a randomized, double-blind trial. Randomized means chance decided who got which treatment. Double-blind means neither the teenagers, their families, nor the study staff knew who was on the medicine. Placebo is an injection that looks the same but contains no medicine.

Participants received either liraglutide 3.0 mg or placebo by injection under the skin once daily, on top of lifestyle therapy for everyone.

The primary outcome was the change in the BMI standard-deviation score at week 56. Body mass index (BMI) compares weight with height. Because children and teens are still growing, researchers use a standard-deviation score, which shows how far a young person's BMI sits from what is typical for their age and sex. A drop in the score means BMI moved closer to the typical range.

What they found

At week 56, the BMI standard-deviation score fell more in the liraglutide group than in the placebo group. The estimated difference was -0.22, with a 95% confidence interval of -0.37 to -0.08 (R32-C80). A confidence interval is the range in which the true difference most likely sits. The range does not include zero, so the result is unlikely to be due to chance.

The abstract also reports an estimated difference between groups of -4.64 percentage points for BMI, -4.50 kg for body weight, and -5.01 percentage points for relative weight change, all favouring liraglutide.

After the medicine was stopped, the BMI standard-deviation score rose more in the former liraglutide group than in the former placebo group during the 26-week follow-up. The estimated difference was 0.15, with a 95% confidence interval of 0.07 to 0.23 (R32-C81). In plain terms, some of the benefit reversed once treatment ended.

Side effects and people who stopped

Stomach and bowel side effects were more common with liraglutide: 81 of 125 participants (64.8%) compared with 46 of 126 (36.5%) on placebo.

Side effects led 13 participants (10.4%) in the liraglutide group to stop the trial treatment, compared with none in the placebo group (R32-C82). Serious side effects were uncommon in both groups: 3 (2.4%) with liraglutide and 5 (4.0%) with placebo.

One suicide occurred in the liraglutide group. The trial investigator assessed it as unlikely to be related to the trial treatment. The summary we reviewed does not report the overall number of people who left the trial for any reason.

What this study does not tell you

• Adolescents are still growing, so a change in BMI score does not mean the same thing as a kilogram of weight lost in an adult. Results from this trial cannot be compared with adult trials.
• With 251 participants, the trial was too small to detect rare but serious harms.
• Treatment lasted 56 weeks. The trial shows that benefit partly reversed within 26 weeks of stopping, but it does not show what happens with longer treatment or longer follow-up.
• The summary we reviewed does not say how missing data were handled in the analysis.
• The trial did not compare liraglutide with other medicines used in adolescents.
• The trial was funded by the maker of liraglutide.

What it means in Canada

This page describes one trial in adolescents. It does not say whether a medicine is right for any young person. To learn about the medicine itself, see liraglutide in Canada. Information on what provincial plans pay for is at public drug coverage by province, and compare services shows how weight-management programs differ.

Related reading

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

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