MD ThesisIn Britain the incidence of juvenile-onset diabetes in children
appears to be increasing. The incidence in Northamptonshire in 1949 was
1: 7000 children, aged 0- 15 years and a survey of diabetic children of
similar age in Sunderland during a ten year period, 1967-76, revealed an
incidence of 1: 400.
The Sunderland survey comprised ninety-five diabetic children who were
divided into three age groups 0-4 years, 5-9 years and 10 - 14 years.
Overall more boys than girls develop diabetes, particularly in the younger
0-4 year group but girls increase in number and almost equal boys in the
two older groups 5-9 years and 10 - 14 years.
The peak age of onset is eight and eleven years, consisting mainly of
girls; however, boys predominate at twelve years of age. These peak age
ranges related to sex could indicate that the underlying provoking factor
in the aetiology of diabetes at these ages may be adrenarche or puberty.
Environmental factors also appear to play a role in the aetiology of
juvenile-onset diabetes as more diabetic children present with their illness
in the winter six months, October to March. This winter onset tendency was
more significant in the older children (10 - 15 years), and spatial clustering
of the disease in Sunderland children occurred, tending to confirm environmental
influences such as infection in the community. Clustering of cases
was also related to the highter social class areas of the town, consequently
80% of the diabetic children came from social groups I, II and III.
Only 7% of the diabetic children had a first degree insulin dependent
diabetic relative compared to the national figure of 11%. A study of the
extended family history revealed that almost half the Sunderland diabetic
girls and one-third of the boys had a relative with insulin dependent diabetes.
The diabetic child with the phenotypes H. L. A. - B8, BW15 and BW18 had a very significant tendency to an extended family history.
An analysis of the H. L. A. phenotype showed that 75% of the diabetic
children had H. L. A. - B8, BW15 or BW18 phenotype. 53% had H. L. A. - B8
compared to 24% controls. This B8 phenotype accounted for half the children
in each of the three age groups. The majority of boys with H. L. A. - B8
presented in the winter six months, whilst girls with this phenotype presented
evenly throughout the year. This could suggest that the provoking
factor in the aetiology of diabetes in boys with H. L. A. - B8 could be an
infection. The H. L. A. - B40 phenotype, not previously associated with a
diabetogenic tendency, appears to fall into a similar category to boys
with H. L. A. - B8.
The height of the diabetic children at the onset of the illness was
compared to the height of local children and also to the national centile
values. The mean height of the local children (25th centile) was found to
be significantly below the national 50th centile. The Sunderland diabetic
children were equally distributed about the national 50th centile value and
consequently were significantly taller than the local children.
Although 80% of the diabetic children were above the local mean height,
the diabetogenic phenotypes H. L. A. - B8, BW15 and BW18 were not associated
with the very tall diabetic child. Most of the diabetic boys and girls above
the 75th height centile had H. L. A. - B7 or B12 phenotypes. If H. L. A. - B8
was combined with either of these two phenotypes the children were shorter
in stature.
It is possible that the provoking factor in the development of diabetes
in boys with H. L. A. - B8 is an infection, whilst diabetes in girls with
H. L. A. - B8, BW15 or BW18 appears to be related to puberty or adrenarche.
Children with H. L. A. - B7 or B12 may be associated with a different endocrine
imbalance producing excessive tallness prior to diabetes becoming
evident