STEP-TEENS

STEP TEENS is the trial that extended semaglutide to adolescents. Published in 2022, it randomized 201 participants aged 12 to under 18 who had obesity, or excess weight plus at least one weight-related condition, to once-weekly semaglutide 2.4 mg or placebo for 68 weeks, alongside lifestyle support. Ninety percent completed treatment.

The primary measure was the percentage change in BMI rather than weight, because adolescents are still growing and raw pounds are a poor yardstick. Mean BMI fell 16.1% on semaglutide and rose 0.6% on placebo — a 16.7 percentage-point difference. Weight loss of 5% or more was reached by 73% of the semaglutide group against 18% on placebo. Waist circumference, A1C, lipids and liver enzymes all improved more with the drug.

This is the evidence behind the pediatric indications on the Wegovy and Saxenda labels, both of which now cover patients aged 12 and older. It also changed what a pediatrician can offer between lifestyle programs and bariatric surgery, which had previously been the only step up.

The trial did not come without signals worth naming. Gastrointestinal adverse events hit 62% of the semaglutide group versus 42% on placebo, and five participants (4%) on semaglutide developed gallstones, compared with none on placebo — a small number but a real one, and consistent with the gallbladder risk seen in adults. Serious adverse events occurred in 11% on semaglutide and 9% on placebo.

The common confusion is reading the 16.1% BMI figure as 16.1% weight loss. They are different measures, and BMI change in a growing teenager partly reflects height gain. The other frequent question — how long treatment should continue — the trial does not answer, because it ran 68 weeks and stopped.

For a family weighing this: ask how BMI percentile will be tracked, what the plan is around gallbladder symptoms, and who manages the prescription long term. Our STEP TEENS analysis and parent guide go deeper.