type 1 diabetes

[Guest guest]

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his article originally posted January 13, 2009 and appeared in

Issue 451

Study Shows Type I Diabetes Is A Genetic Disease

A 40-year study of identical twins at the Barbara Center for Childhood

Diabetes is finding that four out of five people eventually develop the

disease

after their identical twin gets it first.

But the time lapse before the second twin gets it can be 10, 30 even 50

years.

" This study is telling us that Type I Diabetes is primarily a genetic

disease, " said Dr. Eisenbarth, who is the Executive Director of the

Barbara

Center for Childhood Diabetes at the University of Colorado at Denver

Medical School.

It's also showcasing the roles several different genes play in diabetes and

the steps a family member at risk can take to delay the onset.

" We know Type I diabetes develops because the body's white blood cells

attack and kill the cells that make insulin, " Eisenbarth said.

The 40-year study and a new one tracing 300,000 children at risk for the

disease " tie into our being able to understand how to predict diabetes, " he

said.

" We now have tools to predict and trials to try to prevent Type I diabetes. "

Type I diabetes formerly was called Childhood Diabetes, but it can attack at

any age and is characterized by the body's inability to produce insulin.

By contrast, Type II diabetes usually is associated with lifestyle, such as

obesity, that slows the body's ability to keep blood sugar in balance.

Some 10 percent of the U.S. adult population has one form of the disease or

the other.

Dr. Savage's identical twin developed Type I diabetes back in 1974,

when they were both 27 years old. Identical twins have identical genes, so

he

was certainly susceptible.

Thirty years later, when he was 57, Savage developed the markers for

diabetes. He now gives himself five shots a day to deliver insulin to his

body. His

body still is producing a bit of its own insulin, unlike his brother, who is

completely dependent on injected insulin to keep his blood sugar in balance.

" Before diabetes develops, we can detect antibodies in the blood, "

Eisenbarth said. Antibodies can precede the actual diabetes by 10 or 15

years -- or maybe

by just one year.

" We don't know what the trigger is, after the genetic susceptibility. The

first twin might get it at 12, and the second at 60, " Eisenbarth said.

About 2 in 5 Americans carry a gene that makes them at elevated risk for

Type I diabetes. But the extreme risk comes when a person has inherited

several

genes from both mother and father, patterned in a way that make them

particularly susceptible.

There has been a tremendous increase in Type I diabetes in Colorado and the

nation -- a doubling in just the past 25 years, Eisenbarth said.

" It probably has to do with the environment -- something added or taken away

over the last 70 years, " he said.

Aside from identical twins, if a sibling has diabetes, the other siblings

have about a 1 in 20 chance of getting the disease.

Among people with no family history of the disease, the chances of

contracting Type I are less than one in 300.

Some 40 genes are supposed to contribute to diabetes risk. Most of them are

on chromosome 6.

The Barbara Center is following 300,000 newborns who have at least one

marker for diabetes risk, trying to determine if an environmental trigger

causes

certain of the children to develop the disease.

The kids enrolled in the study get periodic blood tests to see if their

bodies are starting to develop the antibodies to fight diabetes -- usually

the first

sign that the disease is on its way.

Researchers are working on a new approach in which medicines are infused

just once a year to boost the number of regulatory T cells in people at risk

for

diabetes or autoimmune diseases, while slowing the manufacture of dangerous

effector T cells.

" There's a major worldwide effort now to find the set of genes that cause

diabetes, " he said. " Some day, we hope to be able to screen for diabetes and

autoimmune

diseases, and develop therapy to prevent the illnesses.

" Human immunology is finally coming of age and attacking these common

illnesses, " Eisenbarth said. The breakthroughs are a legacy of the Human

Genome Project.

" We're trying to delay the progress, but prevention is the goal. "

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