By Jane Elliott
Health reporter, BBC News
Gareth was diagnosed at 10 weeks
When Gareth Roberts has a sugary drink and a couple of chocolate bars his blood sugar levels soar.
But within hours they are back to normal.
For Gareth, aged 32 from Blackpool, this is a huge change.
At the age of just 10 weeks he was diagnosed with neonatal diabetes and until recently he had to carefully watch what he ate and needed to inject himself with insulin four times a day.
Then doctors diagnosed him with a gene mutation, and he was weaned off insulin and on to tablets that are specially suited for his type of diabetes.
He is delighted with the results.
"After the test result came back positive I was able to come off insulin and go on to tablets," he said.
"Even after eating all the wrong kind of food my blood sugar levels went back to normal without needing any insulin.
"I can eat anything now, but my doctor did warn me to take care and to remember I still had diabetes."
Gareth said diabetes had dominated his life.
"Because I was diagnosed so young I didn't know anything different," he said.
"But it was terrible on insulin - swinging between too low and too high blood sugars.
"I tried to keep a balance, but my blood sugars were always up and down."
Then, two years ago doctors tried him on the tablets.
About one in 100,000 babies are born with neonatal diabetes each year. The condition is diagnosed in the first six months of life.
The pills mean no more injections for Gareth
The standard treatment - regular injections of insulin - helps to control their blood sugar levels to a degree, but cannot prevent fluctuations.
The breakthrough came from a team of scientists at the Peninsula Medical School in Exeter.
Using DNA testing, they showed that about half of the children with this condition had a mutation in a key gene which prevented them from releasing insulin in response to a rise in blood sugar levels.
They also found a potential answer: a group of drugs called sulphonylureas, which are already used to treat people with type 2, or adult onset, diabetes.
Sulphonylureas help people with neonatal diabetes to release insulin from their own pancreas.
Two researchers - Professor Andrew Hattersley, from Peninsula and Professor Frances Ashcroft, of the University of Oxford - who played a leading role in the discovery recently held a meeting of parents, patients, doctors and scientists.
Professor Ashcroft said it had been exciting for the scientists to see the effect the drug had on patients.
"It was a wonderful day. As a scientist working on a human disease, you hope that your work will help patients one day," she said.
"But you never expect that it will have an impact in your own lifetime, and you certainly never expect to meet people whose lives have been helped by it.
"To have some one say 'You have transformed my life' is extraordinary".
Professor Hattersley said the new treatment really had transformed patients' lives.
"As soon as the problem was discovered, patients can be given the drugs," he said.
Neonatal diabetes is diagnosed in the first six months of life
It affects one in 100,000 babies
Although neonatal diabetes produces no insulin it is different from the more common type 1
"This has had a fantastic effect because their blood sugar levels are very much more stable.
"Gareth was struggling with diabetes and trying to balance things with insulin - his life has now changed dramatically.
"The key message we have been getting out to doctors and patients is that anyone diagnosed with diabetes under six months should have genetic testing.
"This treatment does not work in patients who do not have the genetic change."
'My life back'
Gareth said the Exeter and Oxford teams have given him back his life.
He initially got a letter from his local hospital in Blackpool, inviting him to give a blood sample.
"They said it was a complete shot in the dark and might not affect me, but that if it did it would transform my life.
"And it has. Within six weeks of taking these tablets I had stopped taking insulin.
"Now I have no insulin at all, which is such a relief.
"At the time I was having four injections a day and you have to keep on taking the blood sugars, but since I have been on the tablets it has been great.
"I take one in the morning and one at night but I am not tied to when I take them. Every time I take a blood test now it is normal."