To report the incidence of insulin-dependent diabetes mellitus (IDDM) in the Province of Pavia, Italy, in the 0- to 29-year-old age-group between 1988 and 1992. Urban versus rural residence, socioeconomic level, and family size of IDDM cases were also investigated.
A prospective register was established in 1988 to collect all newly diagnosed IDDM patients with onset before 30 years of age. The primary data source was based on notification of new cases by hospitals, out-patient clinics, family doctors, and pediatricians. The secondary and independent data source consisted of the registries of prescriptions for insulin syringes in the health districts of the province.
In 5 years (1988–1992), 66 cases of IDDM in the 0- to 29-year-old age-group were identified. The completeness of ascertainment was 100% for the combined sources. Age-adjusted (world-standardized) incidence rates per 100,000 (95% confidence interval) were 9.52 (6.42–13.61), 6.72 (4.68–9.34), and 8.27 (6.42–10.58), respectively, for the age-groups 0–14, 15–29, and 0–29. The rates were higher for residents in urban areas. The number of children in the families of IDDM patients was significantly higher than in the reference population.
Our data indicate the concordance of IDDM incidence rates with the North-Italian rates and a possible association of the disease with environmental factors. These factors might enhance the susceptibility to IDDM in genetically predisposed individuals.