The family of a teacher who suffered from a “highly dangerous” eating disorder and took her own life have won a fresh inquest into her death, after arguing lessons could be learnt to prevent others dying in similar circumstances.

Megan Davison, 27, from Cheshunt, Hertfordshire, was found hanged at her home on August 4 2017.

She had suffered from Type 1 diabetes and diabulimia, a psychiatric disorder involving the deliberate omission of insulin doses.

At an inquest in March 2018, the senior coroner for Hertfordshire concluded that Ms Davison’s death was suicide.

Her mother Lesley Ann Davison later brought a High Court challenge seeking a fresh inquest into her daughter’s death, arguing that new expert evidence on diabulimia showed there was a public interest in more being known about “the dangers” of the condition.

A fuller exploration into Ms Davison’s death could also lead to a “prevent of future deaths” (PFD) report because of the evidence on “systemic issues” around the treatment of the “poorly understood” disorder that had an “unacceptably high” mortality rate, the court was told.

In a written judgment issued on Thursday, Lord Justice Holroyde and Mr Justice Garnham set out details of the case and their reasons for quashing the coroner’s original conclusion and ordering a fresh investigation.

They said Ms Davison, who had been under the care of the Community Eating Disorder Service at Hertfordshire Partnership University NHS Foundation Trust, had previously been treated for mental health issues, had taken insulin overdoses and was in hospital with an eating disorder.

Staff were previously concerned she might take her own life.

The judges said the coroner had not made a PFD report and had proceeded on the basis that diabulimia, which he described as a “terrible intractable eating disorder”, was a rare condition.

But a report by Professor Khalida Ismail, professor of psychiatry and medicine at King’s College, London, and a “leading expert in diabetes and diabulimia”, made it clear that the condition is “worryingly, a more widespread disorder than is commonly recognised”, judges said.

The report, that led to the Attorney General authorising Mrs Davison’s legal challenge, said about 400,000 people in the UK have Type 1 diabetes and that a estimated one third “omit some insulin for fear of weight gain”.

Those with severe diabulimia “are at very high risk of acute and chronic diabetes complications and premature mortality”, the report said.

It explained that there was “no pathway of care” for the condition and healthcare professionals do not routinely screen for it nor ask patients if they are omitting insulin.

“Prof Ismail made a number of criticisms of the care which Megan had received, and expressed her opinion as to the potential value of a new inquest in increasing understanding of the nature and incidence of diabulimia, which could lead to more screening and assessment of patients and so reduce the number of deaths”, judges said.

Adam Straw KC, representing Mrs Davison, argued that a new inquest could lead to a PFD report because of the “systemic issues” raised by the professor, which “may be of public importance, because diabulimia is a highly dangerous but poorly understood disorder, with a high mortality rate and many preventable deaths”.

Coroners are provided with a duty to make PFD reports to people or organisations, including local authorities or government departments, where they believe that action should be taken to prevent future deaths.

Mr Straw argued that Ms Davison’s parents wanted a fresh investigation “so that they can fully understand how Megan met her death, and so that lessons can be learned with a view to preventing others dying in similar circumstances”.

Bridget Dolan KC, representing the coroner, said he took a neutral stance to the High Court challenge, and argued that he was “not under a duty to take proactive steps to seek out additional evidence which might give rise to a duty to make a PFD report”.

She also said that nothing in Prof Ismail’s report gave rise “to any realistic prospect of a finding that Megan’s death was caused by neglect”, judges said.

The judges concluded that the professor’s report indicated a need for “better coordination” over the treatment of diabulimia, that there might be “deficiencies” in care, that “warning signs and ‘red flags’ were not acted upon in Megan’s case” and that “inadequate care may have contributed to Megan’s decision to take her own life”.

They said it was “possible” a new inquest could lead to a PFD report but this will be for the different coroner to decide.

“Prof Ismail’s evidence shows a public interest in more being known about the dangers of diabulimia,” the judges said, adding that the availability of new evidence “may result in a different view being taken as to whether any act or omission in the care of Megan may have contributed to her death”.

The judges ruled that Ms Davison’s death be considered by a different coroner.