Diabetes incidence in 0- to 14-year age-group in Italy: a 10-year prospective study

The Registry for Type 1 Diabetes Mellitus in Italy (RIDI) Study Group was established to coordinate the registries of type 1 diabetes in Italy. This report is based on 3,606 children younger than 15 years diagnosed with type 1 diabetes and prospectively registered during 1990-1999 by nine centers, covering >35% of the Italian population.

Registries were pooled in four geographic macro-areas: north, central, south, and insular. The completeness of registration was assessed by the capture-recapture method. Poisson regression analysis was used to evaluate temporal trend in incidence.

Large variations in incidence were confirmed not only between Sardegna and the mainland but also among peninsular areas. In Sardegna, there was an excess of boys (the boy-to-girl incidence ratio was 1.4). The overall incidence showed average increases of 3.6% (P <0.001) and 3.7% (P <0.001) per year in peninsular Italy and in Sardegna, respectively. Significant increases in incidence rates were found in boys aged 10-14 years (6.7%, 95% CI 0.5-13.3) and in girls aged 5-9 years (6.6%, 0.5-13.1) living in the southern area. The incidence rate also increased in boys aged 10-14 years (5.0%, 0.3-10) and in girls aged 0-4 years (4.9%, 0.8-9.1) living in Sardegna.

Italy is a country with large geographical variations in incidence rates of type 1 diabetes. However, the rates are evenly increasing both in the mainland and Sardegna, suggesting that similar environmental factors are operating over populations that have different genetic backgrounds.