The US approval of a drug that can delay the onset of type 1 diabetes represents the “start of a seismic shift” in treating the condition, a British charity has said.

Teplizumab is a type of immunotherapy that works by tackling the root cause of diabetes rather than just its symptoms.

The drug tells the immune system not to attack pancreatic cells which produce insulin. These are vital for controlling blood glucose levels.

In type 1 diabetes, the pancreas no longer makes insulin, so people have to inject it to keep their blood sugar levels steady.

Type 1 diabetes affects about 400,000 people in the UK, including more than 29,000 children.

Symptoms, such as feeling very thirsty, passing urine more than usual, losing weight without trying and being very tired, can come on quickly, particularly in children.

If left untreated, type 1 diabetes is life-threatening.

Chris Askew, chief executive of Diabetes UK, said: “Today’s landmark approval of teplizumab in the US is the start of a seismic shift in how type 1 diabetes is treated.

“For 100 years, people living with type 1 diabetes have relied on insulin to treat the condition, and today’s decision means that for the first time, the root cause of the condition – an immune system attack – can be tackled and type 1 diabetes potentially delayed for up to three years.

“The licensing of teplizumab in the UK must now be accelerated, and we’re working with the NHS and with other diabetes charities and key stakeholders to ensure that people in the UK can benefit from this life-changing treatment as soon as possible.”

Mr Askew said preventative treatments for type 1 diabetes must be combined with screening programmes to identify people at risk.

He added: “Diabetes UK is funding immunotherapy research to help people at all stages of type 1 diabetes, and we hope this monumental breakthrough will open the door for increased research investment, to develop further effective immunotherapies to treat the condition.

“Today is a significant moment in the history of type 1 diabetes and one that will shape the future – propelling us closer to the day where type 1 diabetes can be prevented or cured altogether.”

The JDRF charity, which funded a trial into the drug, said teplizumab also has the potential to slow progression of the illness in the long term.

Karen Addington, chief executive of JDRF UK, said: “The world now has a drug which is proven to effectively tackle the root causes of type 1 diabetes, delaying the onset of the condition and slowing down disease progression.

“Our work now focuses on securing approval in the UK. We will also be leading further research into the future potential of teplizumab to entirely prevent type 1, helping to eradicate this condition from everyone’s lives.”