Why Type 1 diabetes cases will double worldwide by 2040
• COVID-19 infection may increase the risk of type 1 diabetes as one in five of all deaths from disease is in under-25s
The number of people living with type 1 diabetes worldwide is expected to double by 2040, with most of the new cases among adults living in low- and middle-income countries, new modelling data suggests.
The forecast, developed from available data collected in the new Type 1 Diabetes Index, provides estimates for type 1 diabetes rates, associated mortality, and life expectancy for 201 countries for the year 2021.
The authors wrote: “The worldwide prevalence of type 1 diabetes is substantial and growing. 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 per cent rate of diagnosis in all countries.
The new findings were published in the journal Lancet Diabetes & Endocrinology. The T1D Index Project database was published in September.
According to the model, about 8.4 million people were living with type 1 diabetes in 2021 with one-fifth from low- and middle-income countries. An additional 3.7 million died prematurely and would have been added to that count had they lived. The estimate is that about one in five of those who died because of type 1 diabetes in 2021 were younger than 25 years and had undiagnosed diabetes.
Senior vice-president of the European Association for the Study of Diabetes and an endocrinologist based in Belgium, Dr Chantal Mathieu, said: “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.”
By 2040, the model predicts that between 13.5 and 17.4 million people will be living with the condition, with the largest relative increase from 2021 in low-income and lower-middle-income countries. A majority of both incident and prevalent cases of type 1 diabetes are adults, with an estimated 62 per cent of 510,000 new diagnoses worldwide in 2021 occurring in people aged 20 years and older.
Meanwhile, according to new research at this year’s European Association for the Study of Diabetes (EASD) yearly Meeting in Stockholm, Sweden (19-23 Sept), testing positive for Severe Acute Respiratory Syndrome Coronavirus Type 2 (SARS-CoV-2), the virus that causes COVID-19, is associated with an increased risk of new-onset type 1 diabetes in children and adolescents.
The study is by Hanne Løvdal Gulseth and Dr. German Tapia, Norwegian Institute of Public Health, Oslo, Norway, and colleagues.
The study used national health registers to examine new-onset type 1 diabetes diagnoses made in all youngsters aged under 18 in Norway (over 1.2 million individuals) over the course of two years, starting on March 1, 2020, comparing those who contracted COVID-19 with those who did not.
Lead author and Research Director at the Norwegian Institute of Public Health, Dr. Hanne Løvdal Gulseth, said: “Our nationwide study suggests a possible association between COVID-19 and new-onset type 1 diabetes. However, the absolute risk of developing type 1 diabetes increased from 0.08 per cent to 0.13 per cent, and is still low.
The vast majority of young people who get COVID-19 will not go on to develop type 1 diabetes but it is important that clinicians and parents are aware of the signs and symptoms of type 1 diabetes. Constant thirst, frequent urination, extreme fatigue and unexpected weight loss are tell-tale symptoms.”
It has long been suspected that type 1 diabetes, which is usually diagnosed in younger people and is associated with the failure of the pancreas to produce insulin, is a result of an over-responsive immune reaction, possibly due to a viral infection, including respiratory viruses.
Several recent case reports have suggested a link between new-onset type 1 diabetes and SARS-CoV-2 infection in adults. But evidence is more limited to children. A recent United States Centre for Disease Control and Prevention (CDC) report found that American children were 2.5 times more likely to be diagnosed with diabetes following a SARS-CoV-2 infection, but it pooled all types of diabetes together and did not account for other health conditions, medications that can increase blood sugar levels, race or ethnicity, obesity, and other social determinants of health that might influence a child’s risk of acquiring COVID-19 or diabetes.
In this nationwide study, Gulseth and colleagues linked individual-level data from national health registries for all children and adolescents in Norway (1,202,174 individuals). Data were obtained from the Norwegian preparedness register that is updated daily with individual-level data on Polymerase Chain Reaction (PCR)-confirmed SARS-CoV-2 infections, COVID-19 vaccinations and disease diagnoses from the primary and secondary health care services.
Children who were followed from March 1st 2020 (the start of the pandemic) until the diagnosis of type 1 diabetes, turned 18 years old, died, or the end of the study (March 1st 2022), whichever occurred first.
The researchers examined the risk of young people developing new-onset type 1 diabetes within or after 30 days after PCR-confirmed SARS-CoV2 infection. They compared this group with children and adolescents in the general population who did not have a registered infection, as well as to a group of children who were tested but found to be negative for the virus.
Over the two-year study period, a total of 424,354 children tested positive for SARS-CoV-2 infection and 990 new-onset cases of type 1 diabetes were diagnosed among the 1.2 million children and adolescents included in the study.
After adjusting for age, sex, country of origin, geographical area and socio-economic factors, the analyses found that young people who contracted COVID-19 were around 60 per cent more likely to develop type 1 diabetes 30 days or more after infection compared to those without a registered infection or who tested negative for the virus.
Gulseth said: “The exact reason for the increased risk of type 1 diabetes in young people after COVID-19 is not yet fully understood and requires longer-term follow-up and further research into whether the risk could be different in children who are infected with different variants.
“It is possible that delays in seeking care because of the pandemic might explain some of the increases in new cases. However, several studies have shown that SARS-CoV-2 can attack the beta cells in the pancreas that produce insulin, which could lead to the development of type 1 diabetes. It’s also possible that inflammation caused by the virus may lead to exacerbation of already existing autoimmunity.”
The authors acknowledged that the study was observational and does not prove cause and effect, and they cannot rule out the possibility that other unmeasured factors (for example, underlying conditions) or missing data may have affected the results. They also note that they only included children who took a PCR test, not a lateral flow test or asymptomatic infections, in the analyses, which may limit the conclusions that may be drawn.