The incidence of type 1 diabetes in the age group 0-39 years has not increased in Antwerp (Belgium) between 1989 and 2000: evidence for earlier disease manifestation.
OBJECTIVE
A worldwide increase in the incidence of childhood type 1 diabetes has been observed. Because in various countries the majority of new type 1 diabetic patients are diagnosed in adulthood, we investigated whether the rising incidence of this disorder in children reflects a global increase in the incidence of diabetes or a shift toward earlier clinical presentation.


METHODS
The incidence of type 1 diabetes presenting before age 40 years was prospectively measured in the Antwerp district over a 12-year period (1989-2000). The completeness of ascertainment was evaluated by the capture-recapture method. Trends in incidence during the study period were analyzed by Poisson regression.


RESULTS
The incidence of type 1 diabetes diagnosed before age 40 years remained constant over the 12-year period, averaging 9.9 cases per 100,000 individuals per year. The incidence was similar in both sexes under age 15 years, but a marked male excess was noted for adult-onset disease, in particular after age 20 years, resulting in a male-to-female ratio of 0.9 under age 15 years vs. 1.6 thereafter (P = 0.001). During the 12-year observation period, there was a significant tendency toward increasing incidence under age 15 years at the expense of a decreasing incidence between ages 15 and 40 years (P = 0.025). The annual increase in incidence averaged 1.8% under age 15 years and 5.0% under age 5 years (P = 0.06).


CONCLUSIONS
Our results indicate that in Belgium, the increasing incidence of childhood type 1 diabetes-especially for children under age 5 years-is not attributable to a global increase in disease incidence, but rather to earlier clinical manifestation. The results suggest that an environmental factor may preferentially accelerate the subclinical disease process in young diabetes-prone subjects.
Weets
Ilse
I
Diabetes Research Center, Free University, Brussels, Belgium.
De Leeuw
Ivo H
IH
Du Caju
Marc V L
MV
Rooman
Raoul
R
Keymeulen
Bart
B
Mathieu
Chantal
C
Rottiers
Raoul
R
Daubresse
Jean-Claude
JC
Rocour-Brumioul
Danielle
D
Pipeleers
Daniel G
DG
Gorus
Frans K
FK
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D001530:Belgium / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012044:Regression Analysis; D017678:Sex Distribution; D013997:Time Factors