ANALYSIS OF THE GEOGRAPHIC-DISTRIBUTION OF THE INCIDENCE OF DIABETES-MELLITUS TYPE-I IN CATALONIA (SPAIN)

BACKGROUND: The aim of the present study was to evaluate the geographic distribution of the incidence of diabetes mellitus type I (DMI) in Catalonia from 1987-1990. METHODS: The base of the study is the Catalonian registry of incidence of DMI in the period from 1987-1990. The definition criteria were: diagnostic criteria of diabetes (WHO norms 1985), age of diagnosis under 30 years, residence in Catalonia in the period of diagnosis and exclusion of other types of diabetes. The population at risk was estimated according to the general census of the population of 1986. The total incidence of Catalonia was calculated by provinces and counties according to the Poisson distribution. RESULTS: The incidence of DMI observed in Catalonia was of 11.5/100,000 inhabitants per year (CI 95 %, 10.6-12.4) in the age group from 0-14 years and 10.7/100,000 inhabitants per year (CI 95 % 10.1-11.3) in the age group from 0-29 years. The exhaustivity in the detection of the cases was of 90.3 %. No differences were found in interprovincial incidence in the 0-14 age group: Barcelona 11.6 (10.6-12.7), Girona 10.2 (7.2-13.4), Lleida 11.7 (7.7-15.8), Tarragona 10.5 (7.6-13.5). In the 15-29 age group a lower incidence was observed in Tarragona. The incidence by counties varied between 2.9 and 15.0/100,000 inhabitants per year with those of greatest incidence being observed in the Valles Oriental (15.0/100,000 inhabitants/years), Alt Penedes (14.5/100,000 inhabitants/year), Segria (15.0/100,000 inhabitants/year) and the Priorat (13.7/100,000 inhabitants/year). CONCLUSIONS: No differences were found in the incidence of diabetes mellitus type I in the four Catalonian provinces. Distribution by counties was more heterogeneous without defining zones with a much higher incidence to that observed in the whole of Catalonia.