Celiac disease (a condition that damages the small intestine) may boost the risk of type 1 diabetes. But that may not be where the damage ends. Celiac disease could lead to problems down the road for diabetes patients.
Type 1 diabetes patients who have had celiac disease for more than 10 years may have a higher risk of diabetes-related eye damage, compared to patients without celiac disease.
Celiac disease is a condition that damages the small intestine, keeping it from absorbing healthy parts of foods. The damage happens because of a reaction to gluten - a substance found in wheat, barley and rye among other foods.
Kaziwe Mollazadegan, MD, of Karolinska Institutet in Sweden, and colleagues recently set out to see if celiac disease affects the risk of diabetic retinopathy (damage to the eye's retina caused by long-term diabetes) in people with type 1 diabetes.
They found that patients had a lower risk of diabetic retinopathy in the first 5 years after being diagnosed with celiac disease, compared to patients without celiac disease, with a hazard ratio of 0.57.
Hazard ratios explain how often an event happens in one group versus another. A hazard ratio of less than 1.0 means the event happens less in on group than the other. In this case, the event (diabetic retinopathy) happened less often in those who had celiac disease for less than 5 years compared to those without celiac disease.
When patients had celiac disease for more than 10 years, however, their risk of diabetic retinopathy increased, with a hazard ratio of 2.83 for those with celiac disease for 10 to 15 years and 3.01 for those with celiac disease for 15 years or more.
Celiac disease did not appear to affect the risk of diabetic retinopathy in patients who had the condition for 5 to 10 years.
These findings suggest that type 1 diabetes patients with long-standing celiac disease may have a higher risk of developing diabetic retinopathy than patients without celiac disease.
"Importantly and sadly, there was no ability for the authors of this study to comment on the patients compliance with their gluten-free diets," said Steven Kussin, MD, FACP, author of Doctor, Your Patient Will See You Now, a patient’s guide to our medical system and resource for issues advancing patient advocacy.
"This was unfortunate. If this information was available, the authors may have been able to show that [those with poor dietary compliance] alone were at particular risk for eye disease compared to those who were strictly avoiding gluten," said Dr. Kussin, who was not involved in the study.
"Many patients with celiac disease are poorly compliant with diet because they were diagnosed by screening and never had symptoms. Many celiac disease patients eat gluten with no clinical symptoms. That's why many celiac disease patients are still eating gluten," he said.
According to the authors, the study's results suggest that people with type 1 diabetes and long-term celiac disease should be watched closely for signs of diabetic retinopathy.
"Monitoring is important. But so is prevention," said Dr. Kussin.
"Why diagnose a complication of a disease if it's possible to prevent it altogether? Not all people with genetic susceptibility to diseases like celiac disease and type 1 diabetes actually get them. Some observers think that fewer than 10 percent of those at risk with a bad genetic profile will develop a clinical disease. The environment plays a big role in turning high risk profiles into an actual disease and then making that disease a life altering burden by increasing the likelihood of its complications," he said.
In other words, instead of dealing with diabetic retinopathy once it develops, doctors and patients can take steps to prevent the complication altogether.
"Both diseases have a genetic component and an environmental trigger that activates it. The environment patients live in, and the diets they consume can trigger genetic changes long after your genes are set in stone at the time of conception," said Dr. Kussin.
"This is a process called epigenetics. It’s getting a lot attention today. Just last week in breakthrough studies published in Nature, it was found that junk DNA is no longer junk. It contains the switches that activate or inactivate our genes. These switches were shown to be active in celiac disease. It is possible that poor compliance with the celiac disease can trigger the 'junk' DNA to switch on inflammatory proteins that go on to affect the eyes of those with type 1 diabetes," he said.
For their research, Dr. Mollazadegan and colleagues studied 41,566 diabetes patients who were at least 30 years of age when they were diagnosed with diabetes. A total of 947 type 1 diabetes patients were diagnosed with celiac disease over the course of the study.
The study was published September 10 in Diabetes Care, a journal of the American Diabetes Association.