Incidence of type I diabetes mellitus in Navarre, Spain (1975–91)

The aim of this study was to ascertain the incidence of Type 1 diabetes mellitus in Navarre, an autonomous community in northern Spain. Subjects were patients who presented with diabetes between 1975 and 1991, age range 0-16 years, resident in Navarre at the onset of symptoms. Endocrinologists in outpatient centres and hospitals (both public and private) in Navarre were the primary source of data, while secondary sources were: independent general practitioners, health centre paediatricians and the Child-Youth Diabetics Parents' Association of Navarre. The degree of ascertainment was 97.8%. Average annual incidence of diabetes detected was 9.54/100000 (95% CI 8.2-11.1) in the 0-14 year-old group. The least incidence was observed in 1976 and highest in 1990. The incidence in males (9.71/100000) was higher than in females (7.83/100000). The highest incidence was observed in the 10-14 year-old group (13.70/100000) when analysed by groups. No seasonal variation in the onset of diabetes was observed. These results suggest a significant increase in the incidence of type 1 diabetes between 1975 and 1991.