Large incidence variation of Type I diabetes in central-southern Italy 1990-1995: lower risk in rural areas

Aims/hypothesis. To evaluate the relation between the incidence of childhoo d Type I (insulin-dependent) diabetes mellitus and the degree of urbanizati on in the central-southern part of Italy. Methods. The incidence was determ ined in two areas: area A encompasses 3 regions of central-eastern Italy (M arche, Abruzzo, Umbria), whereas area B encompasses one southern region (Ca mpania). During 1990-1995, 706 children aged 14 or under with insulin-depen dent diabetes mellitus of recent onset were registered. The completeness of the case ascertainment in the registries analysed separately for each regi on was high, ranging from 96.3 % to 99 %, Results. The age-standardized inc idence was higher in area A (9.6 per 100 000 person per year; 95 % confiden ce interval: 8.5-10.8) than in area B (5.4 per 100000 person per year; 95 % confidence interval: 4.9-6.0), In both areas the standardized incidence ra tios increased with the degree of urbanization (chi-squared for trend: area A = 140, p < 0.0001; area B = 79, p < 0.0001). The highest standardized in cidence ratios were in the most urban communities. Conclusion/interpretatio n. This study showed a statistically significant difference in incidence of childhood insulin-dependent diabetes mellitus among different areas of the continental peninsula of Italy. People living in the rural communities app ear to have a lower risk.