Personalising treatments for patients with Maturity Onset Diabetes of the Young
Mary had been injecting herself with insulin twice a day for 28 years before one day, a correct diagnosis from the globally pioneering team at the University of Exeter Medical School meant she was ‘free from insulin injections’. As is the case for up to 90 per cent of patients with Maturity Onset Diabetes of the Young (MODY), Mary had wrongly been told she had Type 1 Diabetes, meaning she was prescribed insulin that she did not need.
It was only when the Exeter team confirmed HNF1A MODY (the commonest cause of UK MODY) by molecular genetic testing that she could switch to a tiny dose of a tablet regularly used in the treatment of Type 2 diabetes that meant she could stop her insulin injections. MODY is most often identified in those diagnosed with diabetes below the age of 25 years who also have a parent with diabetes, like Mary they may be treated with insulin from diagnosis but actually continue to make insulin of their own.
Mary Lee, aged 57 years from Essex, said: “I had been injecting insulin for 28 years and the first time that I didn’t do the injection it was wonderful, I couldn’t believe it. I refer to the genetic test as the best blood test I ever had, the one that was to free me from the restraints of insulin injections.”
Thanks to the work of the team in Exeter thousands of patients worldwide have now gained a better quality of life. Since the mid 90s, they have been involved in work to identify different genetic causes of MODY. There is another sub-group of patients with Glucokinase MODY, who do not need any treatment at all. Their blood sugar is naturally elevated, but research shows they are not at risk of resulting complications.
Professor Maggie Shepherd, who is part of the Exeter team, said: “MODY is caused by a change in a gene which is just like a simple spelling mistake. Using new technology, we can now identify these spelling mistakes among the library of DNA data. We know that this change can be passed down from a parent to a child, so each child has a 50 per cent chance of inheriting the same genetic change. It’s really important that we identify the specific cause of diabetes as early as possible, so we can ensure patients get the most efficient, effective treatment, and in many cases spare them from having to inject themselves several times a day.”
The tablets, known as sulfonylureas, are at least as effective, and in some cases better, for glycaemic control in patients with MODY. The switch from insulin often sparks a significant improvement in quality of life, with some patients reporting less fluctuation in blood glucose levels.
For Dan Humphries, aged 26 from Shropshire, injecting insulin was taking its toll on several aspects of his life when the ‘big day’ came when he was able to transfer from insulin injections to a once daily tablet in May 2005, and he was able to turn his prospects around. He said: “I can’t emphasise enough how different it’s been. I was looking to fail college and then to get out with ‘A’s’, get into vet school and spend the year doing physical work with animals, it’s fantastic’
His mother added: “I cannot tell you what a huge relief it has been to get an exact diagnosis and the appropriate treatment. The change for Dan is immense. Being diagnosed with diabetes was bad enough, but watching him inject himself four times a day, having hypos to the point we couldn’t leave him alone was a nightmare.”
For Margaret Smith, 61 years from Derbyshire, the change to tablets heralded freedom and convenience. She said: “It’s made a vast difference, you can go anywhere and not have to worry about taking insulin with you, you just pop a tablet in your mouth and that’s it, it’s quite normal really.”
Already, international guidelines on diagnosis have changed, and now the Exeter team is working to ensure that more people get the right diagnosis as soon after diagnosis of diabetes as possible. Professor Shepherd said: “Exeter is an international centre of excellence in genetic types of diabetes, and health care professionals can use our online MODY probability calculator to identify those patients most likely to benefit from genetic testing. People with diabetes can also contact us directly if they think they may have MODY, via our website http://www.diabetesgenes.org.”