Semaglutide in children: Iceland cohort

A nationwide retrospective cohort study published in Pediatric Obesity in August 2026 has produced the first real-world picture of subsidised semaglutide use in children with obesity in Iceland^[1]. The findings are notable not just for the weight outcomes -- which are strong -- but for what universal subsidisation made possible: a treatment-persistent cohort in a single healthcare system, with no commercial filter on who got access.

This article explains what the researchers found, how it fits alongside the controlled trial data, and what questions it leaves open. It is written for educational purposes. It is not medical advice, and nothing here is a recommendation to start, stop, or adjust any treatment. Those decisions belong with a clinician who knows the individual case.

The study: design and population

Thorsteinsdottir and colleagues at Landspitali University Hospital collected longitudinal anthropometric data on all children aged 12 and above with grade 2 obesity who received subsidised semaglutide under Iceland's universal reimbursement policy between March 2021 and June 2025^[1]. The final cohort was 113 participants. Mean age was 15.2 years. Forty-four percent were female. The study used piecewise linear mixed-effects regression to model BMI trajectories before and after treatment started, expressed as percentage of the age- and sex-specific International Obesity Task Force threshold for grade 2 obesity (a measure called %IOTF30).

The design is retrospective and observational -- no placebo arm, no randomisation. That is a limitation worth naming clearly. What it trades for those methodological constraints is population-level coverage: because Iceland subsidises treatment universally and the country is small, the dataset is close to a census of eligible treated children rather than a selected sample from a specialist clinic.

What the numbers show

Before semaglutide, BMI in this cohort was climbing at roughly 0.29 percentage points of %IOTF30 per month -- a trajectory consistent with progressive obesity over years^[1]. On treatment, that trajectory reversed to -0.86 percentage points per month. Projected forward, the model estimates a reduction of 5.17 percentage points at six months and 10.33 percentage points at twelve months. Sixty-three percent of participants achieved reductions exceeding 10 percentage points, which the authors treat as a clinically meaningful threshold.

Those numbers sit inside the range established by the randomised controlled trial evidence. STEP TEENS, the Weghuber et al. double-blind, placebo-controlled trial in 201 adolescents aged 12 to 17 with obesity, reported a mean BMI change of -16.1% with semaglutide 2.4 mg at 68 weeks versus +0.6% on placebo, with 73% of the treated group achieving at least 5% weight reduction at week 68^[2]. The Icelandic cohort does not contradict those figures; it fills in what happens outside a tightly controlled trial protocol, in a real population, through a universal healthcare system.

Neurodevelopmental status: what the data could and could not show

A subgroup of 56 participants was evaluated for whether having a neurodevelopmental disorder modified the treatment response^[1]. The analysis found no statistically significant difference (p = 0.83). The authors are careful here: they flag that the subgroup was not large enough to have adequate statistical power to detect a real difference if one existed. The result is informative but not conclusive. Children with neurodevelopmental conditions are disproportionately represented in paediatric obesity cohorts, and whether their response to GLP-1 class medicines differs from the general paediatric population remains an open research question.

What universal subsidisation adds to the picture

In most healthcare systems, access to subsidised weight-management pharmacotherapy for children depends on navigating specialist referral pathways, meeting narrow reimbursement criteria, and sometimes waiting for capacity. Iceland's universal reimbursement policy removed those filters for children with grade 2 obesity^[1]. The practical result is a more demographically representative cohort than most specialist-clinic series, and higher treatment persistence -- because the cost barrier that drives early discontinuation in other settings was absent.

High persistence matters because the weight-regain literature in this class is well established. The STEP-4 discontinuation trial showed that participants who had lost weight on semaglutide and then switched to placebo regained a large share of that weight. A healthcare system that subsidises the drug but cannot support sustained use is not delivering the full clinical value of the treatment. The Icelandic experience suggests that universal coverage can support the persistence needed for meaningful outcomes.

How this fits the existing evidence base

The semaglutide evidence base for paediatric obesity is younger than the adult literature but is growing. The FDA approved Wegovy (semaglutide 2.4 mg) for chronic weight management in adolescents aged 12 and above in December 2022, based primarily on the STEP TEENS data^[2]. Real-world studies from single healthcare systems add a layer the controlled trials cannot provide: evidence that the outcomes are achievable in clinical practice, not just in trial conditions. The Icelandic cohort is notable because it represents an entire country's eligible paediatric population rather than a selected sample.

What the study does not address: long-term safety in this age group, the safety signal profile (adverse-event data are not the focus of this retrospective cohort), what happens after treatment stops, or whether outcomes generalise to paediatric populations with different baseline characteristics, healthcare contexts, or treatment durations. The authors acknowledge these gaps. They are not minor.

What to take from this study

The Icelandic cohort adds real-world weight to a pharmacological case that the controlled trial data had already made. Children with grade 2 obesity in a universal healthcare system, treated with subsidised semaglutide, reversed a progressive weight trajectory that was running in the wrong direction. The majority achieved clinically meaningful reductions. The policy implication -- that universal subsidisation both widens access and supports persistence -- is relevant for healthcare systems deciding how to structure paediatric obesity treatment.

The clinical implication is more cautious: this is one observational cohort from one small country. Decisions about whether any individual child should start or continue semaglutide treatment need to weigh individual clinical circumstances, family context, access to dietary and lifestyle support, monitoring capacity, and the age-specific safety evidence base, none of which this article can evaluate. That conversation belongs with a paediatrician or specialist with access to the full clinical picture.