Research reveals type 1 diabetes is more common in older adults than perceived

by Barbara Hewitt on December 4, 2017

Adults are as likely to develop type 1 diabetes as children, with more than 40% of type 1 diabetes cases occurring after the age of 30, new research has found.

It has long been thought that type 1 diabetes is a condition that manifests itself in childhood and it is rare to develop the disease as an older adult, but new research from the University of Exeter medical school has found otherwise.

Elderly Patient

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Many of those diagnosed with type 1 diabetes after the age of 30 are thought to have type 2 diabetes at first, and not initially treated with insulin to control blood sugar levels. Indeed, previous research from the university showed that it took a year for those with type 1 diabetes who had been misdiagnosed with type 2 to be put on insulin.

Among the adults with type 1 diabetes to have been misdiagnosed is Theresa May, the British Prime Minister, who was initially told by doctors she had type 2 diabetes and given tablets which did not control her blood sugar.

The researchers point out that distinguishing between type 1 or type 2 diabetes matters as it affects the treatment needed. In type 1 diabetes immune cells destroy the body’s insulin producing beta cells and people need to be injected insulin to control blood sugar levels. With type 2 diabetes there is still insulin produced so it can be treated initially with diet and tablet therapy.

Type 1 diabetes is harder to recognise and correctly diagnose in adults because far more people develop type 2 diabetes in later life. Type 2 accounts for 96% of diabetes cases between the ages of 31 and 60, the research shows.

A crucial clue to the possibility of adult–onset type 1 diabetes is the failure of tablets to control blood glucose. Adult onset type 1 patients are also likely to be slim compared to type 2 patients who are often obese.

Exeter University’s diabetes research team concluded that, although much less common than type 2 diabetes in adulthood, it is crucial that type 1 is diagnosed and treated correctly as it can be life threatening.

Indeed, they found that one in nine of the adult onset type 1 diabetes were admitted to hospital with diabetic ketoacidosis, a potentially fatal condition that develops when type 1 patients are not given insulin.

The study is the first to use a novel genetic analysis to identify type 1 diabetes in adults. This allows them to identify cases of type 1 diabetes not picked up by the patients’ doctors.

‘Diabetes textbooks for doctors say that type 1 diabetes is a childhood illness. But our study shows that it is prevalent throughout life. The assumption among many doctors is that adults presenting with the symptoms of diabetes will have type 2 but this misconception can lead to misdiagnosis with potentially serious consequences,’ said Dr Richard Oram, a senior lecturer at the University of Exeter and consultant physician.

Andrew Hattersley, professor of molecular medicine at the University of Exeter and consultant diabetologist at the Royal Devon and Exeter NHS Foundation Trust, explained that the diagnosis of type 1 diabetes in middle and old age is very difficult because almost all patients with diabetes at this age have type 2.

‘Failure to recognise that the diabetes is type 1 rather than type 2 and give appropriate insulin treatment can be dangerous. Type 1 diabetes should be considered for any patient who is rapidly failing to respond to increasing doses of tablets especially if they are slim,’ he said.

It was only when she took part in the Start Right study, led by the University of Exeter, that Helen Philbin discovered that she actually had type 1 diabetes and had been on the wrong medication for a year. The metformin she was prescribed was only worsening her symptoms including vomiting and weight loss.

Slim and active, she felt her lifestyle could not have triggered the condition. ‘Having the wrong diagnosis was extremely frustrating. I just knew it wasn’t right. I’m an active person. I’m always running around with my two young kids and I walk the dog every day,’ she explained.

Helen had just turned 40 when she visited her GP after experiencing extreme thirst. Although she was underweight, her blood test strongly indicated diabetes. She was diagnosed with type 2 and prescribed metformin, and sent on a course to learn about lifestyle factors including a low sugar diet.

‘All the other people on the course were in their mid 60s and overweight. I stood out like a sore thumb. When I raised it with nurses or my GP, I was told that type 1 diabetes is always diagnosed in childhood, so I had to be type 2. I felt like I was banging my head against a wall,’ she said.

Helen took the lifestyle advice seriously. She cut out carbs form her diet almost completely to get better blood sugar control but she began vomiting up to four times a week. ‘Even a single piece of toast would send my blood sugar levels through the roof, and I was losing even more weight,’ she pointed out.

‘I’m so pleased I was invited to take part in the trial and I got the right diagnosis. It’s such a relief and it’s made such a difference. I’m fine now. I haven’t had a single episode of vomiting since switching to insulin and I’m now gaining weight. My year on the wrong treatment was awful. I hope this research ensures more people can get the right treatment more swiftly,’ she added.

The opinions expressed in this article do not necessarily reflect the views of the Community and should not be interpreted as medical advice. Please see your doctor before making any changes to your diabetes management plan.

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