05 May 2025
Institute news
Picture a person with type 1 diabetes: they might be a child or teenager, perhaps a young adult. What about someone in their seventies? While it has been typically viewed as a disorder of youth, research out of the Baker Heart and Diabetes Institute has found the type 1 diabetes population now looks very different, Dr Dee Tomic reports.
The population with type 1 diabetes in Australia and across the globe has changed in recent decades. Technologies such as insulin pumps and continuous glucose monitoring have made it easier for people with type 1 diabetes to manage their blood glucose control. At the same time, complications of diabetes, such as cardiovascular and kidney diseases, are arising less often due to better management of risk factors, including medications for high blood pressure and high cholesterol.
As a result, people with type 1 diabetes first diagnosed in childhood are living longer, while greater numbers of older adults are being newly diagnosed with type 1 diabetes. Our research from the Baker Heart and Diabetes Institute, published in the journal Nature Reviews Endocrinology, brings together findings from 25 population-wide studies of type 1 diabetes in older adults to show the changing face of type 1 diabetes.
Key findings from the new research
New cases of type 1 diabetes may be as common, or even more common, in some populations of older adults compared to children. In one study from Sweden, the greatest number of new type 1 diabetes diagnoses across all age groups of children and adults occurred in those aged 70–79 years. Similarly, in Ireland, those aged 75 years and above had the highest rate of new type 1 diabetes cases.
However, in many other countries, including the United States, China, Spain, and Japan, new-onset type 1 diabetes remains most common in childhood. Part of the difference between countries may be explained by their demographics and healthcare systems. Another contributing factor is the way type 1 diabetes is measured, with some studies using self-reported type 1 diabetes, while others use blood tests or hospital records.
Because of this, it is difficult to say whether new-onset type 1 diabetes in older adults is really as common as it is in children. However, the total population with type 1 diabetes, including new and existing diagnoses, is clearly shifting towards older ages.
In Australia, 33 per cent of those with type 1 diabetes in 2015 were aged over 60 years, while 63 per cent were aged over 40 years. Similar findings were reported in studies from the United States and Scotland.
Older adults with type 1 diabetes also have reduced life expectancies compared to those of the same age without diabetes. An Australian analysis found that the remaining life expectancy of those with type 1 diabetes aged 60–64 years was 6.5 years shorter for men and 8.5 years shorter for women compared to those in the general population of the same age.
Another study reported that older Australian adults with type 1 diabetes had death rates that were two to three times higher than those in the general population. Similar findings were reported in Spain, Denmark, Latvia, Scotland, and the United States.
Diagnostic challenges in older age
Differentiating type 1 from type 2 diabetes in adults, especially older adults, is a challenge that requires careful judgment. As type 2 diabetes accounts for approximately 90–95 per cent of diabetes cases, even a small proportion of those with type 2 diabetes being misclassified as type 1 would greatly inflate type 1 diabetes numbers.
Since more people are diagnosed with type 2 diabetes as adults than as children, misclassification of type 1 diabetes is more likely at older ages. There is a substantial overlap in the clinical presentation of adult-onset type 1 and type 2 diabetes, making diagnosis challenging.
Some of the blood markers that are used to diagnose type 1 diabetes in childhood wane over time, to the point that they may even be absent in older adults being investigated for diabetes. Other markers may be present at similar levels in those with adult-onset type 1 diabetes and those of the same age with type 2 diabetes.
Further complicating things is Latent Autoimmune Diabetes in Adults, or LADA, which shares features of both type 1 and type 2 diabetes. LADA is between three and 12 times more common than type 1 diabetes in older adults, according to studies from Europe, China, and the United Arab Emirates.
There is still no agreement on whether LADA represents a less aggressive version of type 1 diabetes, a mixture of type 1 and type 2 diabetes, or a separate condition. Clinicians and researchers are calling for clarification of diagnostic definitions so the picture of type 1 diabetes in adults can be fully understood.
Implications and future directions
It is important to know the extent to which type 1 diabetes is occurring in older adults compared to youth, as this population requires a different approach to management. As the life expectancy of people with type 1 diabetes improves, the picture of type 1 diabetes will shift further towards an increased number of older adults with complex care needs.
Compared to children and younger adults, older adults with type 1 diabetes are particularly vulnerable to the consequences of extremely low blood glucose levels. They also have an increased risk of cognitive decline, depression, and frailty.
A feature of type 1 diabetes that is not well-recognised is the large proportion of middle-aged or older adults, which our research found to account for over half of all people with type 1 diabetes in several countries. This is important for healthcare professionals and service providers to know so that adequate support can be arranged for these people.
Older people with diagnosed or suspected type 1 diabetes and their families should discuss a tailored approach to management with their care team. The changing face of type 1 diabetes is a result of our improved understanding of diabetes and its treatment, which will continue to evolve and enable people with type 1 diabetes to live healthy and fulfilling lives.
This article has been reproduced with the permission of Diabetic Living Magazine.
