WHO GETS TYPE 1 DIABETES?
Up to 1,000,000 people in the US are
estimated to have type 1 diabetes, with about 30,000
new cases diagnosed each year. It is much less common
than type 2, however, consisting of only 7% to 10% of
all cases of diabetes. Nevertheless, like type 2 diabetes,
the incidence in type 1 has been rising over the past
few decades in certain regions of the US and some European
countries, particularly in Finland and England.
Risk Factors in Children
Type 1 can occur at any age but usually
appears between infancy and the late 30s, most typically
in childhood or adolescence. Boys and girls are equally
vulnerable. Studies report the following may be risk
factors for developing diabetes type 1:
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Being ill in early infancy.
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Not being breast fed and drinking
cow's milk in infancy. One study found that children
fed cow's milk in the first eight days of life had
twice the risk as those on breast milk. The risk
is still very low and likely to develop in children
who have a genetically impaired immune response
to dietary proteins. Breast milk contains factors
that may help regulate the immune response and prevent
diabetes in such children. A major study is underway
to determine if avoiding cow's milk for the first
six to eight months will prevent type 1 diabetes.
National differences in risk also suggest that not
all cow's milk is the same and some proteins carry
higher risks than others.
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Having an older mother.
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Having a mother with type 1 diabetes.
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Having a mother who had preeclampsia
during pregnancy.
-
Obesity in children has long been
linked to a higher risk for type 2 diabetes. Two
2001 studies reported an association between high
weight at birth and obesity during childhood as
risk factors for type 1 diabetes as well. The common
risk factor may be an increase in insulin secretion,
which occurs with obesity. This theoretically could
overstress the beta cells so that they become susceptible
to damage by overactive immune factors (particularly
cytokines), and eventually destruction in children
genetically vulnerable to type 1 diabetes.
Until recently, diabetes in children
was almost always type 1 diabetes. Of major concern,
however, are estimates that between 8% and 45% of new
diabetes cases in children are now type 2, most likely
because of the increase in childhood obesity. [ See
Well-Connected Report #60, Diabetes Type 2.]
Having Other Immune Abnormalities
Autoimmune Diseases. The incidence
of type 1 is higher than average among people with other
autoimmune diseases, including Grave's disease, Hashimoto's
thyroiditis, Addison's disease, multiple sclerosis (MS),
and pernicious anemia. Research, in fact, has raised
the possibility that all autoimmune diseases share a
common genetic basis. A 2001 study found, for example,
that the T-cell immune factors in type 1 diabetes target
the same self-antigens as in multiple sclerosis (MS).
And both diseases have been associated with cow's milk
protein. Many questions are unanswered, however. It
is not known why the diseases develop in different locations
to cause separate disorders or why some autoimmune events
occur in everyone but not everyone develops an autoimmune
disease.
Asthma and Allergies. There has been some work
suggesting that people with asthma and allergic diseases
are less likely to develop diabetes type 1.
Both these conditions and diabetes type 1 are on the
increase and all are triggered by abnormal T-cell responses.
The specific T cells involved, however, differ between
diabetes and the asthmatic or allergic responses. (T-cells
are important immune cells that produce factors causing
inflammation.) It is possible, then, that all of the
conditions occur when common environmental assaults
trigger an immune response, but the specific T-cells
involved would depend on individual genetic factors.
Ethnicity
There is a very wide variation in incidence
of type 1 among population groups. Type 1 diabetes appears
to be most common in people of northern European descent
and in specific Mediterranean groups (such as Sardinians).
It is less common among Asians and African Americans.
Still, African Americans with type 1 diabetes are 50%
more likely to die from it than Caucasians are, mostly
due to lower-quality health care. |