The genetic testing of babies diagnosed with diabetes in the UK is making a real difference to their lives, doctors say.

And according to the researchers behind the breakthrough, the use of genetic testing could be extended to help treat other conditions.

Over the last decade the time it takes to screen babies with diabetes has fallen from over 4 years to just under 2 months.

They are immediately tested for all possible 22 genetic causes where as previously they would only get genetic testing years after the disease was diagnosed and then the genes would be tested one at a time.

The breakthrough now means that the genetic diagnosis is made early, giving doctors information on how best to treat the baby and give their parents information on the medical problems they are likely to develop in the future.

In the past symptoms were used to select which gene would be tested – now the early comprehensive gene testing means that the genetic result predicts clinical features that have not yet developed.

This means doctors can anticipate the likely problems for their patients and put the appropriate care in place to reduce their impact.

Researchers at the University of Exeter Medical School have based their findings on the results of genetic testing for the 22 known genetic causes of neonatal diabetes in 1,020 patients over the past 10 years.

Professor Andrew Hattersley said: “In the last decade, we have shown that making a precise diagnosis from genetic testing results in improved treatment and hence we now get samples soon after diabetes is diagnosed from patients throughout the world.

“Now the ability to test all genes in a single test means we are able to accurately inform patients and their doctors – not just about the best treatment but also about likely medical problems before they have started.

“This means doctors can start to develop treatment to either prevent or improve these problems.

“In the past, genetics has been used to confirm a diagnosis and that often took years. Now genetics is being used to give an early, precise diagnosis - this changes how healthcare is practised, and will be seen in many areas in medicine in the future.”

The study, which was funded by the Wellcome Trust and Diabetes UK, is published in The Lancet this week.

Alasdair Rankin, director of research at Diabetes UK, said: “It’s vital that children with neonatal diabetes get early access to genetic testing, so they can receive the correct treatment as soon as possible.

“We are proud to have supported this groundbreaking work, which has capitalised on recent genetic advances to boost our understanding and make a real difference to the lives of children with this rare condition.”

This week Diabetes UK warned that the rising numbers of people being treated for the disease “threatens to bring down the NHS”.

Cases in England and Wales have risen by almost 60 per cent in the past decade – as an additional 1.2 million adults are now living with the condition compared to 10 years ago.

The charity said treating diabetes costs the NHS nearly £10 billion a year of which 80 per cent was spent on managing avoidable complications.

And it predicted that if the current trends continue, five million people will have diabetes by 2025.

How genetic diagnosis for diabetes has been transformed

The transformation in the approach to genetic testing over the past 10 years can best be seen in the experiences of families of babies with diabetes.

A genetic diagnosis that guides treatment and gives information on associated medical problems is now usual within days of being confirmed with diabetes, while 10 years ago it was typically more than four years before a genetic diagnosis was made.

For one couple from Belfast, a rapid diagnosis has made all the difference to their young son’s treatment.

Paul and Michele Mulligan received a genetic result on then four-month-old baby Matthew within 10 days of taking him into hospital with a rash, and he was found to have high levels of blood sugar.

His consultant sent a sample to the world-leading diabetes genetic team at the University of Exeter Medical School.

Their swift genetic analysis discovered that Matthew’s rare form of neonatal diabetes was caused by a mutation in a single gene, meaning he was not producing insulin and needed insulin therapy, but he will not have problems with his brain or gut unlike many with genetic causes of neonatal diabetes.

The team recommended an insulin pump, which gives insulin through a cannula under the skin, sparing the family the trauma of injecting their son, now aged two, with insulin at meal times.

Mr Mulligan, 30, said: “At first it was horrendous. As a parent, your biggest fear is that your baby is not healthy.

“With Matthew everything seemed fine. He was thriving – putting on weight and developing well, and the rash was the only sign that there was anything wrong.

“Taking him to hospital seemed like a precaution. Finding out he had a permanent form of diabetes felt like the worst thing in the world at the time.

“He was just so small and having constant insulin injections. His blood sugar levels were really unstable and he was like a pin cushion from all the blood tests.

“Although we were shocked and devastated that the genetic tests revealed the condition was permanent, it was a relief that the team recommended the insulin pump.

“By then we’d done our research and we felt that would be the best form of treatment.

“Having a swift diagnosis from the team at Exeter that was so precise was also extremely helpful. Knowing that it’s just one gene that causes Matthew’s condition is reassuring, as we know it’s not got wider implications.

“We’re also hopeful that one day this research may mean treatments can be more targeted.”

Matthew’s 10-month-old sister Emma is unaffected.

For another family, a delayed diagnosis meant their son did not get the most effective treatment.

Emma Matthews’s 15-year-old son Jack was diagnosed with diabetes in the first week of life but the genetic cause was not identified for another five years.

As Jack grew up, Mrs Matthews, a nurse, had to give her son injections but also cope with his unexplained difficulty walking and failure to speak.

When Jack was five Mrs Matthews got a genetic diagnosis of a potassium channel mutation, which explained the diabetes and the developmental delay.

It meant that doctors stopped treating him with insulin and instead prescribed an oral tablet.

Mrs Matthews believes an earlier diagnosis could have made all the difference to her son.

The teenager spoke his first words within weeks of switching from insulin injections to a simple tablet as a result of the diagnosis.

Mrs Matthews, from Essex, said Jack needed round-the-clock supervision before the switch.

“His blood glucose level would go from being stable to being so low that he would collapse on the floor having a seizure, or in a coma,” she said.

“Every day I woke up believing this could be the day that I found Jack unconscious and I wouldn’t be able to wake him up.

“I’m absolutely convinced that, if it wasn’t for the work of the team in Exeter, he would be dead by now.”

Although Jack is now far more stable and happy, he has the mental ability of a four-year-old, and Mrs Matthews believes that he could have been spared some of the damage to his brain if he had had a genetic diagnosis as a baby.

“Learning difficulties are part of Jack’s form of diabetes, but we have met families where the diagnosis came earlier and the impact is much milder,” she added.