C-peptide a reliable guide to residual beta cells across ages, diabetes durations
medwireNews: Levels of circulating C-peptide in people with type 1 diabetes reflect the numbers of remaining beta cells across different ages at diagnosis and durations of disease, confirm UK researchers.
The team looked at 125 pancreatic samples from the Exeter Archival Diabetes Biobank and 111 from the nPOD biobank, all from people who had been diagnosed with type 1 diabetes before the age of 18 years.
Between 88% and 97% of pancreas samples obtained within the first year after diabetes diagnosis still had insulin-containing islets, and this was matched by similarly high rates of detectable plasma C-peptide among 4079 people with type 1 diabetes participating in the UK GRID cohort who were tested in the first year after diagnosis.
At later times after diagnosis, however, levels of both insulin-containing islets in pancreatic samples from deceased donors and C-peptide in living people with diabetes were markedly lower, with this being most striking in those who were diagnosed when they were younger than 7 years.
For example, at 5–10 years’ diabetes duration, just four (29%) of 14 samples from the group who were younger than 7 years at diagnosis still had insulin-containing islets, compared with seven (41%) of 17 and nine (64%) of 14 samples from those aged 7–12 years and 13–17 years, respectively.
By 10 or more years’ diabetes duration, the proportion of detectable insulin-containing islets was down to three (9%) in 34 for a diagnosis age of less than 7 years, and 15% for the older age groups.
“But perhaps, on the more optimistic side […] all hope is not lost for children diagnosed very young, as traditionally thought, as there still is C-peptide and insulin-containing islets present, emphasizing that early intervention is most time-critical in this age group,” said Alice Carr (Institute of Biomedical and Clinical Science, Exeter, UK) who presented the findings at the virtual 56th EASD Annual Meeting.
The pattern of insulin-containing islet loss over time was matched by a decline in C-peptide both for diabetes duration and age at diagnosis, she added.
The same was evident when the team looked at the proportion of remaining insulin-containing islets within pancreatic samples, with this again reducing in line with younger diagnosis age and longer duration of diabetes. Again, this mirrored the C-peptide trends in the UK GRID participants.
“Perhaps this means that prevention trials that delay age at diagnosis may lead to better preservation of beta cells, maintaining higher C-peptide, and if we really want to impact those children diagnosed very young then our intervention needs to be very close to diagnosis,” concluded Carr.
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