Patients with type 1 diabetes have been known to be more prone to another autoimmune disorder, celiac disease, in which gluten in wheat, rye and barley triggers an immune response that damages the small intestine or gut. Now there’s evidence that the two diseases have a genetic link: they share at least seven chromosome regions.
The discovery, published in this week's New England Journal of Medicine, indicates that both diseases may be triggered by similar genetic and environmental mechanisms, such as certain foods, that cause patients' immune systems to become overactive and destroy healthy instead of infected tissue. Previous research has found that celiac disease is five to 10 times more common in people with type 1 diabetes than in the general population, an editorial accompanying the study notes.
"These findings suggest common mechanisms causing both celiac and type 1 diabetes – we did not expect to see this very high degree of shared genetic risk factors," said study co-author David van Heel, a gastrointestinal geneticist at Barts and the London School of Medicine and Dentistry.
Van Heel and his colleagues studied genetic material or DNA from about 20,000 people, half of them healthy, nearly half with type 1 diabetes, and 2,000 with celiac disease. The overlapping genetic variants occurred on regions of chromosomes (parts of cells that carry genetic code) that are believed to regulate the gut’s immune system, the BBC notes.
Type 1 diabetes occurs when a person’s immune system mistakenly attacks healthy beta cells in the pancreas that produce the hormone insulin, which is needed to convert glucose into energy. In celiac disease, a similar attack occurs on the small intestine when sufferers eat gluten-rich grains, causing inflammation in the gut that can lead to bloating, abdominal pain, nausea, constipation, diarrhea, fatigue, anemia, headaches, weight loss and failure to thrive in children. Whereas diabetes 1 patients must inject insulin daily to make up for their deficiency, people with celiac disease can avoid damage and symptoms by sticking to a gluten-free diet.
"The finding raises the question of whether eating cereal and other gluten products might trigger type 1 diabetes by altering the function of the gut and its interaction with the pancreas, the authors write. But Robert Goldstein, chief scientific officer of the Juvenile Diabetes Research Foundation, which helped fund the study, says it would be premature to assume from this study that gluten is also a diabetes trigger.
“I fear the newspaper headlines in the popular press will read like, ‘Eating wheat will cause type 1 diabetes,’” Goldstein tells us. “The presence or absence of these associations has to be linked to some biological consequence” for a person's health.
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