The age at diagnosis of type 1 diabetes continues to decrease in Belgian boys but not in girls: a 15-year survey.
BACKGROUND
The age at clinical onset of type 1 diabetes is decreasing. Preliminary Belgian data suggested that this anticipation occurred preferentially in boys. We investigated whether this gender-specific anticipation could be confirmed over a 15-year observation period.


METHODS
In Antwerp, we studied incidence trends between 1989 and 2003 in 746 type 1 diabetic patients under age 40. For 2928 antibody-positive patients diagnosed nationwide during the same period, age at diagnosis was analysed according to gender and calendar year.


RESULTS
In Antwerp, the incidence of type 1 diabetes under age 15 increased significantly with time from 10.9/100 000/year in 1989-1993 to 15.8/100 000/year in 1999-2003 (p = 0.008). The rising incidence in children was largely restricted to boys under age 10 where the incidence more than doubled during the 15-year period (6.8/100 000/year in 1989-1993 vs 17.2/100 000/year in 1999-2003; p < 0.001). Such an increase was not found in girls under age 10 (p = 0.54). This selective trend toward younger age at diagnosis in boys was confirmed in the larger group of Belgian patients where the median age at diagnosis decreased in boys-but not in girls-from 20 years in 1989-1993 to 15 years in 1999-2003 (p < 0.001).


CONCLUSIONS
Over a 15-year observation period, a selective anticipation of clinical onset of type 1 diabetes was found in boys but not in girls. This suggests that an environmental factor may preferentially accelerate the sub-clinical disease process in young boys.
Weets
I
I
Diabetes Research Center, Free University Brussels, Belgium. ilse.weets@uzbrussel.be
Rooman
R
R
Coeckelberghs
M
M
De Block
C
C
Van Gaal
L
L
Kaufman
J-M
JM
Keymeulen
B
B
Mathieu
C
C
Weber
E
E
Pipeleers
D G
DG
Gorus
F K
FK
D000293:Adolescent; D017668:Age of Onset; D001530:Belgium / Q000453:epidemiology; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology*; D005260:Female; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D008297:Male; D012727:Sex Characteristics