Incidence of type 1 diabetes in Navarre, 2009-2012

Abstract

Background. A north-south gradient for the incidence of type 1 diabetes (DM1) has been described in Europe, with higher incidence in the northern countries. The aim of this study is to describe the incidence data for DM1 in Navarre from 2009-2012, regardless of age at diagnosis, including geographical distribution and age and sex characteristics.

Patients and methods. Prospective study, based on one primary and three secondary sources. Completeness of records was assessed, using the capture-recapture method, at 98.42%.  Incidence was compared between different gender and age groups by estimating the incidence ratio using Poisson regression methods. To compare the incidence between the different geographical areas, adjustments were made to the values obtained by the indirect standardization method.

Results. A total of 216 cases were detected (incidence: 8.4/100,000 population/year; 95 % CI: 7.3-9.5). Incidence was higher in children than in adults, although the number of new cases was highest in those aged over 15. The age group with the highest incidence was 10 to 14 years; however, the highest percentage of patients fell in the 15 to 29-year-old group.  Incidence was higher in men than in women. The incidence rates in the three southern regions were generally higher than the mean for Navarre.

Conclusions. Navarre has a very high incidence of DM1 in children and adults aged 15 to 29. DM1 is more common in men and shows some geographic variability.