A new immunotherapy drug can delay the onset of symptomatic type 1 diabetes by up to three years, offering patients a period free from the relentless demands of insulin management for the first time in more than a century. Teplizumab, marketed as Tzield and manufactured by Sanofi, has been approved by the National Institute for Health and Care Excellence (Nice) for use on the NHS in England and Wales.
Approval and eligibility
Nice gave the green light on Tuesday for adults and children aged eight and older who have early, pre-symptomatic type 1 diabetes, known as stage 2. These individuals have autoantibodies associated with the disease and abnormal blood sugar levels but no symptoms. The drug is not a cure, but postpones the progression to symptomatic stage 3 diabetes. The UK regulator’s decision follows a rigorous and transparent evaluation balancing clinical benefit and value for taxpayers, according to Helen Knight, director of medicines evaluation at Nice. Sanofi has reached a commercial agreement with NHS England for a confidential discounted price, it is understood. NHS England now has 90 days to set up services, while NHS Wales has 60 days to make the treatment available. Access in Scotland and Northern Ireland is being decided separately, with processes underway to determine next steps.
How teplizumab retrains the immune system
Teplizumab is an immunotherapy that targets the autoimmune process at the root of type 1 diabetes. In people with the condition, the immune system mistakenly attacks and destroys the insulin-producing beta cells in the pancreas. The drug works by binding to CD3 receptors on T-cells, modulating their signalling. This process is thought to increase the number of regulatory T-cells (Tregs) and induce a state of anergy or programmed cell death in autoreactive T-cells, effectively suppressing the immune system’s assault on pancreatic beta cells. By preserving the body’s own insulin production for longer, teplizumab delays the point at which patients become dependent on injected insulin.
Clinical trials have demonstrated significant delays in disease progression. In one key study, 43% of patients who received teplizumab progressed to symptomatic stage 3 diabetes, compared with 72% in the placebo group. The median time to diagnosis in the teplizumab group was 48.4 months, versus 24.4 months for those given a placebo. Another study showed that 50% of treated patients remained free of diabetes, compared with only 22% in the placebo group. The TrialNet study reported a median time to diagnosis of approximately 60 months — five years — for the teplizumab group, against around 27 months — just over two years — for the placebo group. The drug has also been shown to preserve beta-cell function as measured by C-peptide levels, an indicator of remaining insulin production. In a trial of newly diagnosed patients, treatment with teplizumab maintained or improved insulin production after one year, and the phase 3 PROTECT study found it significantly slowed the decline in mean C-peptide levels compared with placebo.
Impact on patients and the diabetes landscape
The approval marks a historic shift in type 1 diabetes treatment, moving beyond insulin for the first time since its discovery 105 years ago. Insulin replaces what the body cannot produce but does not alter the course of the disease. Teplizumab, by contrast, targets the underlying cause. Dr Elizabeth Robertson, director of research at Diabetes UK, described the decision as a landmark: “For the first time in 100 years, we are moving beyond insulin, with a medicine that targets the root cause of the condition. This is an extraordinary moment for celebration in the type 1 diabetes community, and represents a shift towards a future where type 1 diabetes can be prevented altogether.” She added that the drug offers years free from the relentless demands of managing the condition with insulin, as well as valuable time to prepare.
For children and teenagers in particular, the delay allows more time to reach key developmental milestones before facing the lifelong burden of diabetes management. The postponement of symptomatic disease can also help prevent long-term complications such as eye, kidney and heart disease. Karen Addington, chief executive of the charity Breakthrough T1D, said: “For the first time, we have an immunotherapy that can delay the onset of symptomatic type 1 diabetes. If it were your child or someone you love, you would want to do everything possible to give them more years without the daily burden of managing this relentless condition.” Breakthrough T1D UK played a key role in funding early-stage research and facilitating regulatory pathways. The drug was first developed at the University of Chicago in partnership with Ortho Pharmaceuticals and later advanced by MacroGenics with Eli Lilly. The Type 1 Diabetes TrialNet consortium conducted pivotal studies, collecting data from more than 200,000 relatives of people with type 1 diabetes over 20 years, which led to the development of disease staging. The US Food and Drug Administration first approved teplizumab in November 2022 for stage 2 patients aged eight and older, and expanded that indication in April 2026 to include children as young as one year old. The European Medicines Agency issued a positive recommendation in November 2025.
Administration and side effects
Teplizumab is given as a one-off course via an intravenous drip into a vein once a day for 14 consecutive days. Each infusion takes about 30 minutes. The dose starts low and gradually increases over the first few days. Once the 14-day course is complete, treatment ends. Common side effects observed in clinical trials include rash, headache, diarrhoea, leukopenia (low white blood cell count), lymphopenia (low lymphocyte count), neutropenia and increased liver transaminases. A boxed warning exists regarding serious and life-threatening cases of viral reactivation, including Epstein-Barr virus and cytomegalovirus. Lymphopenia is a common side effect that can affect the body’s ability to fight infections, though white blood cell counts typically begin to normalise after the fifth dose. An integrated safety analysis of five clinical trials found that most adverse events were self-limited and no long-term adverse effects were observed in some earlier studies.
The arrival of teplizumab has been welcomed as the start of a new era in type 1 diabetes treatment. Researchers continue to study how long the drug’s effects last and why some patients benefit more than others. TrialNet is exploring other drugs and combinations to delay or prevent the condition altogether, and investigations are underway into whether earlier use in younger children is feasible and appropriate. The median time to diagnosis in the TrialNet study stood at approximately 60 months for those who received teplizumab, compared with roughly 27 months for the placebo group — a difference that underscores the drug’s potential to reshape the outlook for thousands of people at risk of this lifelong condition.