Læknablaðið : fylgirit - 01.06.1982, Blaðsíða 32

20
PLENARY LECTURE
FACTORS IN THE AETIOLOGY OF TYPE 1 DIABETES IN
ICELAInIDIC BOYS. T. Helgason, M.R. Jonasson. Diabetic
Clinic, Landspitalinn, University Hospital,Reykjavik.
A total survey'of diabetics taking insulin showed
that Type 1 diabetes represented 90.5%. The pre-
valence of this type of diabetes was 1.2/1000 and
the mean annual incidence was stable at 6.2/100 000
over the 10 year period 1970-'79 with a trena for
the time of diagnosis to coincide with that of viral
epidemics. The prevalence at diagnosis differed
significantly between the two main towns and was
highly significantly lower in rural areas. At the
time of diagnosis ('70-'79) there was a male excess
of 51% whereas in the prevalence figures it had fall-
en to 29%. There was a significantly increased in-
cidence between July and January in the age group
diagnosed at 0-14 years but seasonal variation was
not significant in the age groups 15-29 and^-30.
A remarkable finding was the high preponderance of
births in the month of October of male children dia-
gnosed at 0-14 years of age (p<0.00001). These
'October boys'revealed a strikíng association with
the HLA specificities known to confer an increased
risk of developing diabetes. They were diagnosed
more often before the age of five than would be ex-
pected and showed no seasonal variation in diagnosis.
HLA types and virus infections were considered as
possible causes of this striking finding but there
seemed to be at least one additional seasonal factor
acting prenatally. Circumstantial evidence is pre-
sented thab this additional factor is the N-nitroso
compound content of processed mutton traditionally
consumed in the two weeks from December 23. Analysis
of recently produced Icelandic smoked/cured mutton
has confirmed the presence of considerable concentra-
tions of N-nitroso compounas.