One in five cases of Type 1 diabetes are diagnosed in the over-40s, new figures suggest, prompting warnings that people may become seriously ill before they realise.
Type 1 is usually diagnosed between the ages of 10 and 14 but the National Diabetes Audit data shows a substantial number are over 40, with some over 69.
In the year 2011/2012, 8,952 people were diagnosed with Type 1 diabetes. This included 2,035 people who were over 40, including more than 500 who were over 69.
The new data was unveiled at Diabetes UK's annual Diabetes Professional Conference in Liverpool.
It accompanies a new study from the Royal Gwent Hospital in Wales which suggests that lack of awareness about late-onset Type 1 diabetes is leading to some people becoming seriously ill.
Symptoms of Type 1 include being tired, thirsty, losing weight and going to the toilet a lot, especially at night.
Simon O'Neill, director for health intelligence and professional liaison for Diabetes UK, said: "This study highlights that Type 1 diabetes is not just a condition that strikes the young. We hear of reports where people who develop the condition later in life are only diagnosed once they are seriously ill.
"This is why it is really important that healthcare professionals do not rule out the possibility of symptoms being Type 1 just because the person is older."
Dr Triveni Shekaraiah, lead researcher for the study said: "Type 1 diabetes is a very serious condition that predominantly develops in the young but our study shows that clinicians and the general public need to be aware of the possibility of the onset of Type 1 diabetes in older patients."