Managing type 1 diabetes is old hat to 31-year-old Catherine Oddenino. The New Yorker has had the disease since she was 11, and is adept at counting carbohydrates and dosing insulin. But in her mid-20s she was thrown a curveball. Whenever she ate something, she felt like she had food poisoning.
After a visit to her doctor, she cut dairy from her diet. But she was also sent to a gastroenterologist who, tipped off by the fact that she had diabetes, immediately tested her for celiac disease. Two weeks later and it was official: the culprit of her “poisoning” was gluten, not dairy.
Now, on top of being keenly aware of how many carbohydrates are in each of her meals and how that will affect her blood sugar levels, Oddenino has to make sure not a speck of gluten is in the food she eats.
Oddenino is by no means the only one living with this dietary juggling act. Study results vary but, according to the American Diabetes Association, an estimated one in 20 type 1 diabetics also has celiac disease. In contrast, the rate in the general population is one in 100.
Diabetes and celiac disease are auto-immune disorders, along with some thyroid diseases, multiple sclerosis and rheumatoid arthritis, among others. This means an overactive immune system causes the body to attack its own cells.
The science is still emerging to explain how type 1 diabetes and celiac disease are related. According to Dr. Alessio Fasano, medical director of the Center for Celiac Research at the University of Maryland, there are two schools of thought: first, the diseases share common genes. A study published in The New England Journal of Medicine in 2008 found almost every gene associated with celiac disease is also involved in type 1 diabetes.
Fasano says another theory is gaining momentum: that some patients have undiagnosed celiac disease which later causes diabetes. While this might seem impossible – typically a celiac disease diagnosis comes long after a diabetes diagnosis – it’s plausible that the celiac disease in these people has simply gone unnoticed.
“You don’t miss [diagnosing] an individual who has diabetes,” says Fasano. In contrast, he estimates that for every person who is diagnosed with celiac disease, at least another 50 aren’t aware they have it. In this “undiagnosed” theory, experts suspect that the chronic “leaky gut” present in celiac patients allows triggers such as food proteins and viral and bacterial particles to enter the body through the intestinal barrier and to reach the space beneath it.
Since a large number of immune cells reside there, this could cause the person to “develop secondary autoimmune conditions, if genetically predisposed,” says Fasano.
Although this “chicken before the egg” question has not been fully answered, the fact remains that most people are diagnosed with celiac disease after already being on a diet for diabetes.
Next: Carbs can get confusing