The number of people living with type 1 diabetes worldwide is expected to double by 2040, with most new cases among adults living in low- and middle-income countries, recent modelling data suggest, and showing that one in five deaths from this condition is in under-25s.
The forecast, developed from available data collected in the newly established open-source Type 1 Diabetes Index, provides estimates for type 1 diabetes prevalence, incidence, associated mortality, and life expectancy for 201 countries for 2021.
The model also projects estimates for prevalent cases in 2040 and is the first type 1 diabetes dataset to account for the lack of prevalence due to premature mortality, particularly in low- and middle-income countries, reports Medscape.
“Worldwide, prevalence of type 1 diabetes is substantial and growing,” wrote the authors. “Improved surveillance, particularly in adults who make up most of the population living with type 1 diabetes, is essential to enable improvements to care and outcomes. There is an opportunity to save millions of lives in the coming decades by raising the standard of care (including ensuring universal access to insulin and other essential supplies) and increasing awareness of the signs and symptoms of type 1 diabetes to enable a 100% rate of diagnosis in all countries.”
“This work spells out the need for early diagnosis of type 1 diabetes and timely access to quality care,” said Dr Chantal Mathieu, MD, at the European Association for the Study of Diabetes (EASD) 2022 annual meeting.
The findings were published in Lancet Diabetes & Endocrinology by Dr Gabriel Gregory, of Life for a Child Programme, New South Wales, Australia, and colleagues.
According to the model, about 8.4m people were living with type 1 diabetes in 2021, with one fifth from low- and middle-income countries. An additional 3.7m died prematurely and would have been added to that count had they lived. One in five of all deaths caused by type 1 diabetes in 2021 is estimated to have occurred in people younger than age 25 years due to non-diagnosis.
“It is unacceptable that, in 2022, some 35 000 people worldwide are dying undiagnosed within a year of onset of symptoms. There also continues to be a huge disparity in life expectancy for people with type 1 diabetes, hitting those in the poorest countries hardest," said Mathieu, senior vice-president of EASD and an endocrinologist based at KU Leuven, Belgium.
By 2040, the model predicts that between 13.5m and 17.4m people will be living with the condition, with the largest relative increase from 2021 in low-income and lower-middle-income countries. Most incident and prevalent cases of type 1 diabetes are in adults, with an estimated 62% of 510 000 new diagnoses worldwide in 2021 occurring in people aged 20 and older.
Type 1 diabetes not predominantly a childhood disease
Mathieu also noted that the data dispute the long-held view of type 1 diabetes as a predominantly paediatric condition. Indeed, worldwide, the median age for a person living with type 1 diabetes is 37-years-old.
“While it is often referred to as ‘child-onset’ diabetes, this important study shows that only around one in five living with the condition are 20 or younger, two thirds are aged 20-64, and a further one in five are 65 or older.
“This condition does not stop at age 18. The children become adults, and the adults become elderly. All countries must examine and strengthen their diagnosis and care pathways for people of all ages living with type 1 diabetes.”
And in an accompanying editorial, Dr Serena Jingchuan Guo, PhD, and Dr Hui Shao, PhD, write that most studies estimating the diabetes burden have focused on type 2 diabetes, noting, “type 1 diabetes faces the challenges of misdiagnosis, underdiagnosis, high risk of complications, and premature mortality”.
The insulin affordability issue is central, say Guo and Shao of the Centre for Drug Evaluation and Safety, Department of Pharmaceutical Evaluation and Policy, University of Florida College of Pharmacy, Gainesville.
“Countries need to strengthen the price regulation and reimbursement policy for insulin while building subsidy programmes to ensure insulin access and to cope with the growing demand for insulin. Meanwhile, optimising the insulin supply chain between manufacturers and patients while seeking alternative treatment options (e.g. biosimilar products) will also improve the situation,” they conclude.
Study details
Global incidence, prevalence, and mortality of type 1 diabetes in 2021 with projection to 2040: a modelling study
Gabriel Gregory, Thomas Robinson, Sarah Linklater, Fei Wang, Stephen Colagiuri, Carine de Beaufort, et al.
Published in The Lancet Diabetes & Endocrinology on 13 September 2022
Summary
Background
Accurate data on type 1 diabetes prevalence, incidence, associated mortality and life expectancy are crucial to inform public health policy, but these data are scarce. We therefore developed a model based on available data to estimate these values for 201 countries for the year 2021 and estimate the projected prevalent cases in 2040.
Methods
We fitted a discrete-time illness-death model (Markov model) to data on type 1 diabetes incidence and type 1 diabetes-associated mortality to produce type 1 diabetes prevalence, incidence, associated mortality and life expectancy in all countries. Type 1 diabetes incidence and mortality data were available from 97 and 37 countries respectively. Diagnosis rates were estimated using data from an expert survey. Mortality was modelled using random-forest regression of published type 1 diabetes mortality data, and life expectancy was calculated accordingly using life tables. Estimates were validated against observed prevalence data for 15 countries. We also estimated missing prevalence (the number of additional people who would be alive with type 1 diabetes if their mortality matched general population rates).
Findings
In 2021, there were about 8·4 (95% uncertainty interval 8·1–8·8) million individuals worldwide with type 1 diabetes: of these 1·5 million (18%) were younger than 20 years, 5·4 million (64%) were aged 20–59 years, and 1·6 million (19%) were aged 60 years or older. In that year there were 0·5 million new cases diagnosed (median age of onset 39 years), about 35 000 non-diagnosed individuals died within 12 months of symptomatic onset. One fifth (1·8 million) of individuals with type 1 diabetes were in low-income and lower-middle-income countries. Remaining life expectancy of a 10-year-old diagnosed with type 1 diabetes in 2021 ranged from a mean of 13 years in low-income countries to 65 years in high-income countries. Missing prevalent cases in 2021 were estimated at 3·7 million. In 2040, we predict an increase in prevalent cases to 13·5–17·4 million (60–107% higher than in 2021) with the largest relative increase versus 2021 in low-income and lower-middle-income countries.
Interpretation
The burden of type 1 diabetes in 2021 is vast and is expected to increase rapidly, especially in resource-limited countries. Most incident and prevalent cases are adults. The substantial missing prevalence highlights the premature mortality of type 1 diabetes and an opportunity to save and extend lives of people with type 1 diabetes. Our new model, which will be made publicly available as the Type 1 Diabetes Index model, will be an important tool to support health delivery, advocacy, and funding decisions for type 1 diabetes.
Type 1 Diabetes Index (Open access)
Medscape article – Type 1 Diabetes Cases Poised to Double Worldwide by 2040 (Open access)
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