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 9.54/100 000 (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 (9.71/100 000) was higher than in females (7.83/100 000). The highest incidence was observed in the 10–14 year-old group (13.70/100 000) 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.