A third of children with type 1 diabetes have signs of other immune system disorders when they get diagnosed with diabetes, according to a new study.

The findings, researchers say, underscore the importance of keeping an eye out for symptoms of those diseases in diabetic children.

Type 1 diabetes is what’s known as an autoimmune disease, where the immune system launches a misguided attack on the body’s own tissue. In the case of diabetes, the assault kills off cells in the pancreas that make the blood-sugar-regulating hormone insulin.

Doctors have known for some time that people with type 1 diabetes also have higher-than-average rates of other autoimmune disorders, including autoimmune thyroid disease, the digestive disorder celiac disease, and Addison’s disease, a disorder of the adrenal glands.

In the new study, researchers wanted to find out how common it is for children to have signs of those three diseases at the time of their type 1 diabetes diagnosis.

They did that by measuring blood levels of certain “autoantibodies” that serve as markers of the conditions. Autoantibodies are immune system proteins directed against the body’s own cells.

Of the 491 children in the study, one-quarter had autoantibodies related to thyroid disease, and one in eight of those children had the disease itself.

Meanwhile, nearly one in eight had antibodies related to celiac disease, and a quarter of those kids had the disease. Five children (or 1 percent of the whole group) had Addison’s autoantibodies, and the disease was confirmed in one of them.

The fact that a third of the kids had signs of other autoimmune diseases means parents and doctors should be on the lookout for the three disorders in diabetic children, according to researcher Dr. Jennifer M. Barker of the University of Colorado Denver, who led the new work.

Autoimmune thyroid disease arises when an immune system reaction causes the thyroid gland to produce either too much or too little thyroid hormone. An overactive thyroid can cause symptoms like nervousness, weight loss, sleep problems and intolerance to heat; an underactive one can cause fatigue, dry skin, hair loss and slow growth in height.

Celiac disease is a digestive disorder in which the immune system reacts to foods with gluten (a protein in wheat, barley and rye), damaging the small intestine. In Addison’s disease, the adrenal glands cannot produce enough of the hormones cortisol or aldosterone, leading to problems like weakness and fatigue, appetite and weight loss, and irritability.

But while the current study used autoantibody testing to screen for the diseases, there are questions about using the tests in actual practice, according to Barker.

Right now, she told Reuters Health in an email, the American Diabetes Association recommends that children with type 1 diabetes be tested for thyroid disease and celiac disease at the time of their diabetes diagnosis. (After that, thyroid screening should be done yearly, and celiac testing if there are potential symptoms.)

Celiac screening has to be done with an antibody test. But doctors can screen for thyroid disease by measuring blood levels of thyroid-stimulating hormone. And there is debate, Barker said, about whether testing for thyroid antibodies would be useful.

“The presence of autoantibodies does not necessarily mean the child will develop the disease,” Barker said.

As for Addison’s disease, there are no guidelines on screening children with type 1 diabetes. But Barker said that parents and doctors should at least keep an eye out for symptoms of the disease - as well as signs of celiac disease and thyroid problems.

In particular, she said, parents should pay attention to their children’s growth and physical development, and keep track of any problems they are having with episodes of low blood sugar, abdominal pain, constipation or diarrhea.

It’s estimated that anywhere from 15 percent to 30 percent of people with type 1 diabetes have autoimmune thyroid disease, while 4 percent to 9 percent have celiac disease, and less than 1 percent have Addison’s.

SOURCE: Diabetes Care, online March 23, 2011.