Semaglutide in type 1 diabetes: Danish data

Semaglutide is approved for type 2 diabetes and obesity. It is not approved for type 1 diabetes anywhere. Yet a growing number of clinicians prescribe it off-label to people with T1D who also carry excess weight, a group that now includes more than two-thirds of adults with T1D in the US and Western Europe. A new Danish registry study, published in The Lancet Regional Health: Europe in May 2026, offers the largest real-world look at what happens when they do^[1].

What the study did

Researchers led by Puriya Daniel Wurtz Yazdanfard and Kathrine Kold Sorensen used Danish national health registries to identify 879 people with type 1 diabetes who filled a semaglutide prescription between 2018 and 2024. Each was matched to controls from the same registries. Follow-up ran up to two years^[1].

The study design is observational, not randomised. The population reflects routine clinical practice in Denmark, not trial-selected patients. That means the results tell us what happened in a real healthcare system, with all the messiness that implies: variable dosing, variable adherence, and patients whose clinicians decided semaglutide was worth trying.

The glycaemic finding

HbA1c in the semaglutide group dropped by about 5.7 mmol/mol (roughly 0.52 percentage points) during the first six months, then stabilised. The matched control groups showed no equivalent change^[1]. A 0.52% HbA1c reduction is clinically meaningful in T1D, where every fraction of a percentage point matters for long-term complication risk.

The median redeemed dose was 1.0 mg weekly, the same dose used in type 2 diabetes treatment with Ozempic. That is worth noting because it suggests clinicians were prescribing at standard doses rather than ultra-low exploratory ones.

Safety: no increase in serious events

The two safety outcomes that matter most in T1D are severe hypoglycaemia (dangerously low blood sugar) and diabetic ketoacidosis (DKA, a life-threatening metabolic emergency). Both are realistic concerns when adding a drug that affects appetite and insulin sensitivity to a person who depends on exogenous insulin. In this cohort, semaglutide use was not associated with an increased rate of hospitalisation for either hypoglycaemia or DKA compared to matched controls^[1].

That safety signal aligns with findings from the smaller, randomised ADJUST-T1D trial published in NEJM Evidence in June 2025, which reported no DKA events and no increase in hypoglycaemia among 36 semaglutide-treated participants with T1D over 26 weeks[2].

The adherence problem

Half the people who started semaglutide had stopped within one year. The cumulative probability of treatment continuation at 12 months was 50%^[1]. The study does not break down why people stopped, whether due to side effects, cost, perceived lack of benefit, or something else. But the number itself is a signal: whatever benefit semaglutide offers in T1D, it is not enough to keep half the users on the drug past a year.

For context, GI side effects (nausea, vomiting, diarrhoea) are the most commonly reported adverse events with semaglutide across all indications. In the ADJUST-T1D trial, 53% of semaglutide recipients experienced GI events versus 25% on placebo[3]. Whether tolerability drove the dropout in the Danish cohort is plausible but unproven.

How this fits with the trial evidence

The Danish cohort study is not the first data point, but it is the largest. Earlier evidence includes a two-year real-world study of 67 adults with T1D published in the Journal of Diabetes Complications, which found HbA1c dropping from 8.2% to 7.1% and daily insulin requirements falling from 1.4 to 0.7 IU/kg/day with no DKA hospitalisations^[4].

The ADJUST-T1D randomised trial (n=72) found that 36% of semaglutide recipients met a composite endpoint of time in range above 70%, time below range under 4%, and at least 5% weight loss, compared to 0% on placebo^[3]. Participants also reduced their insulin doses by about 30% over 26 weeks.

Together, these data sets suggest a consistent direction: semaglutide lowers HbA1c, reduces insulin requirements, and produces weight loss in T1D without triggering the DKA or severe hypoglycaemia events that clinicians worry about most. But the evidence base remains thin compared to the type 2 diabetes and obesity data, and no regulatory agency has approved semaglutide for this use.

What we do not yet know

Several questions remain open. The Danish study does not report weight outcomes, body composition, or cardiovascular markers. It cannot tell us whether the HbA1c improvement translates into fewer long-term complications. The reasons behind the 50% one-year dropout are uncharacterised. And the study population is Danish, a high-income Scandinavian healthcare system with universal coverage; how these results would look in settings with different access patterns is unclear.

No randomised trial of semaglutide in T1D has run longer than 26 weeks. The OBES1TY trial (a multicentre RCT studying semaglutide for obesity in T1D) is expected to complete in 2028. Until longer-duration, larger randomised data arrive, clinicians are working from registry evidence and small trials. That is not nothing, but it is not the foundation that the type 2 diabetes literature provides. For background on semaglutide's approved indications, see our peptide page.

The bottom line

This Danish study is the largest real-world dataset on semaglutide in type 1 diabetes to date. It found a clinically meaningful HbA1c reduction without increased hospitalisations for hypoglycaemia or DKA. It also found that half the users stopped within a year. The data supports cautious exploration, not routine adoption. Anyone with T1D considering semaglutide should discuss it with their endocrinologist, not start it based on registry evidence alone.

This article is for educational and journalistic purposes only and does not constitute medical advice. Semaglutide is a prescription medicine in all jurisdictions we track. Always consult a qualified healthcare professional before using any peptide product.