Background: The aim of the study was to analyze secular trends for increase of annual incidence rates of childhood insulin-dependent diabetes in France between 1988 and 1995.
Methods: The French Registry of incidence of insulin-dependent diabetes in childhood was set up in 1988 in four regions covering more than 2 million subjects aged less than 20 yr. The degree of ascertainment was calculated as 96% between 1988-1995 using data from the prospective catchment of the cases and medical data from the French Social Security.
Results: Standardized annual incidence rates were 7.17 and 9.28 per 100,000, in 1988 and 1995 respectively, assessing a 29% increase for age range at diagnosis 0-19 yr. The trend for increase was statistically significant (r' = 0.95; p = 0.01). The incremental trend of incidence rates was calculated as 0.039 per year following a linear model for increase which proved to predict calculated values not significantly different from observed values for annual total numbers of cases. This increase affected equally both genders, and the younger age group at diagnosis (between 0 and 14 yr.), but not the group 15-19 yr. of age at diagnosis.
Conclusion: The increase in incidence of IDDM was at the same order of magnitude as observed in Nordic countries where the overall incidence rate of IDDM in childhood is at least three times as high as in France. It points towards environmental factors playing a major role in the auto-immune process leading to beta cell destruction. This observation also strengthens the need for research programs on the prevention of the clinical phase of the disease. Such an observation should also supply Health Care providers with important information for future management and organization of IDDM care in childhood.