Background: The incidence of type 1 diabetes in childhood has doubled in Sweden during the last decades. Environmental factors may cause a different disease process, residual beta cell function and clinical manifestation. Insulin therapy has become more intensive. The aim of this study was to examine the clinical characteristics at onset, C-peptide secretion during the first years after diagnosis and if there was any secular trends during the last 25 years.
Methods: All 316 children diagnosed with type 1 diabetes during 1976--2000 and living in the Linköping area were included. Information about clinical characteristics at diagnosis, duration of partial remission, insulin therapy at diagnosis and during the first years was collected from medical records. C-peptide secretion (fasting and stimulated) was measured regularly during the first 5 years. For analysis, the population was divided in five cohorts according to the year of diagnosis.
Results: The clinical characteristics at onset were unchanged as well as duration of partial remission. C-peptide secretion was highest after 3 months and then declined gradually. After 5 years 32.7% of the patients had measurable fasting C-peptide, but only 6.5% > 0.1 nmol/L. HbA1c and insulin doses were lower in patients with persistent fasting C-peptide secretion > 0.1 nmol/L. The cohort 1996--2000 had higher stimulated C-peptide secretion at diagnosis and at 3 months, after longer follow-up there was no difference.
Conclusion: The clinical characteristics at diagnosis, partial remission and duration of C-peptide secretion have remained largely unchanged for the last 25 years.