**2.2 Epidemiology**

The incidence of Type 1 diabetes is increasing worldwide and may double the burden of the disease in youngest children by 2020. Large collaborative studies like DiaMond and EURODIAB Registries demonstrated that one century ago childhood diabetes was rare and fatal, while at the end of the century a steady increase in several parts of the world has been observed. In particular, DiaMond Project reported the trend in incidence of Type 1 diabetes from 1990 to 1999; over this period the average annual increase in incidence was 2.8%, with a slight higher rate in the last 5 year-period as compared to the first 5-year period. Similarly, EURODIAB Study reported a 3.9% annual increase from 1989-2003 (Vehil & Dabelea, 2011). The rising incidence of Type 1 diabetes over the past decades is too quick to be attributed to an increased genetic susceptibility, since the proportion of newly-diagnosed patients carrying the highest-risk HLA genotype (HLA DR3/DR4) seems unchanged.
