Semaglutide in children aged 6–11: what the STEP Young result shows

What the source reports

Novo Nordisk announced on 7 September 2026 that its phase 3 STEP Young trial met its primary endpoint: children aged 6 to under 12 who received once-weekly semaglutide had a greater reduction in body mass index at week 68 than those who received placebo. Both groups also received support with a reduced-calorie diet and increased physical activity.

The company said 40.4% of children in the semaglutide group were below the age- and sex-specific obesity threshold after 68 weeks, compared with none in the placebo group. That means their BMI category had moved to either the overweight or normal-weight range; it does not mean that every child reached a normal-weight category.

The 40.4% result uses a trial-product estimand—an analysis that estimates the effect if all participants had stayed on their assigned treatment. Novo Nordisk has not yet disclosed the average BMI change behind the primary endpoint, the result under an analysis accounting for treatment discontinuation, or the numerical adverse-event data.

How STEP Young was designed

The company describes the younger-child comparison as a randomised, double-blind, placebo-controlled, multinational trial involving 165 children with obesity. More than 85% had class II or class III severe obesity at the start, using paediatric definitions based on a percentage of the 95th BMI percentile rather than adult BMI cut-offs.

Children received semaglutide or matching placebo, with a maximum weekly dose of 1.7 mg or 2.4 mg selected according to starting weight. The 68-week primary analysis measured percentage change in BMI; other outcomes include BMI classification, cardiometabolic measures, glucose metabolism and body composition.

The wider ClinicalTrials.gov record includes both children and adolescents and lists longer follow-up than the first 68-week readout. That matters because the initial announcement is a snapshot from one age cohort, not the complete long-term STEP Young dataset.

Why BMI is interpreted differently in children

A child’s BMI cannot be read like an adult’s because height, weight and body composition change through growth and puberty. Researchers therefore compare BMI with age- and sex-specific reference charts. In the analysis reported by Novo Nordisk, obesity began at or above the 95th percentile.

Moving below that threshold is a meaningful categorical outcome, particularly in a trial where most participants began with severe obesity. It is still only one measure. The announcement does not yet show the distribution of responses, changes in quality of life or physical function, or whether cardiometabolic risk factors improved.

The result also describes a group estimate, not a prediction for an individual child. Variation in growth, baseline health, treatment exposure and treatment discontinuation can all affect outcomes.

What was reported about safety

Novo Nordisk said overall safety and tolerability were consistent with earlier semaglutide and liraglutide trials in adults and younger people, with no new safety concerns and no identified concerns involving growth or pubertal development.

Those statements are reassuring but too general for an independent assessment. The release did not provide the number of children who experienced gastrointestinal effects or serious adverse events, how many stopped treatment, or comparative rates between semaglutide and placebo.

Growth and puberty also require longer observation than a 68-week efficacy readout. The ongoing follow-up and full numerical results will be particularly important because evidence in primary-school-aged children is much more limited than evidence in adults or adolescents.

This result is not an approval for under-12s

A successful phase 3 announcement does not by itself change who can receive a medicine. Regulators review the full evidence, including efficacy, adverse events, dosing, manufacturing and the balance of benefits and risks before deciding whether to extend an authorised age range.

The European Medicines Agency currently describes injected Wegovy as authorised for adults and adolescents from age 12 who meet its criteria; its tablets are for adults. The current US prescribing information likewise establishes weight-management use from age 12 and says effectiveness and safety have not been established below 12.

STEP Young may support future regulatory applications, but Novo Nordisk’s announcement did not report an under-12 authorisation or a timetable for one. The trial result should not be treated as prescribing guidance or as evidence supporting use outside an authorised pathway.

The bigger shift in GLP-1 research

The significance of STEP Young is not a new GLP-1 molecule. It is the movement of an established drug into a younger and clinically sensitive population, part of a wider shift from adult glucose control and weight loss towards long-term treatment of obesity and its complications across different stages of life.

That expansion raises questions that headline weight figures cannot answer alone: when medication should be considered in relation to intensive behavioural support, how development and mental wellbeing are monitored, how families experience long-term treatment, and whether early changes translate into better health years later.

It also changes the standard of evidence. In children, durable health outcomes, development, treatment burden and equity of access deserve at least as much attention as the percentage change on a BMI chart.

What remains uncertain

The principal numerical result remains missing: Novo Nordisk said the primary BMI endpoint was met but did not report the mean percentage change in either group. Without confidence intervals, missing-data analyses and the full statistical plan, the size and precision of the treatment effect cannot yet be evaluated.

Detailed adverse-event rates, discontinuations and adherence have also not been released. The 40.4% figure assumes continued treatment under the trial-product estimand, so a treatment-policy analysis that reflects interruptions or stopping could give a different estimate.

Longer-term questions include how BMI and health markers change through puberty, whether benefits persist during continued treatment, what happens after treatment stops, and whether rare or delayed harms emerge. The company says detailed results are due at ObesityWeek in November 2026; peer-reviewed publication and regulatory assessment would add further scrutiny.

Bottom line

The first STEP Young readout is an important signal: in a controlled phase 3 trial of children aged 6–11, semaglutide plus lifestyle support reduced BMI more than placebo plus lifestyle support, and 40.4% moved below the obesity threshold in the company’s on-treatment-style analysis.

It is not yet a complete evidence package. The main BMI percentages, detailed safety results and longer follow-up remain unavailable, and semaglutide is not currently authorised for weight management below age 12 in the cited EU and US regulatory information. The next meaningful step is the full dataset, not a treatment conclusion drawn from the headline alone.