A Double Diagnosis: Celiac Disease and Diabetes
Celiac and type 1 diabetes are both autoimmune diseases, chronic conditions in which the body’s immune system attacks the very organs it was designed to protect. The two diseases have a genetic link, sharing some genes and environmental factors that may cause the immune system to attack the villi in the small intestine and beta cells in the pancreas.
People with type 1 diabetes are prone to other autoimmune diseases as well, most commonly hypothyroidism, but also less commonly hyperthyroidism, Addison’s disease, vitamin B12 deficiency, vitiligo (spotty loss of skin pigment) and alopecia (hair loss), among others.
An Italian study showed that the prevalence of other autoimmune disorders in patients with celiac disease is related to the duration of exposure to gluten. The older patients were when they were diagnosed with celiac disease, the greater their chances of developing other autoimmune disorders.
While onset of type 1 diabetes can occur at any age, it peaks during the middle childhood ages, from age 6 to 18, says Louis Philipson, MD, PhD, professor in the Departments of Medicine and Pediatrics at the University of Chicago and director of the Kovler Diabetes Center.
In patients with a double diagnosis, often type 1 diabetes is diagnosed first.
“It can be much more subtle to diagnose celiac disease than to diagnose type 1 diabetes. Diabetes, at least in a child, is not usually subtle,” Philipson says. “In children, onset is often very rapid, over a week or a few days, whereas in older kids and adults, the onset can be over months.”
Diabetes symptoms include increased thirst, frequent urination, severe hunger urges and extreme fatigue. In the beginning of the onset period, these symptoms can pass unnoticed by parents until they become severe.
Celiac symptoms can be harder to pin down. Classic childhood symptoms include diarrhea, abdominal pain, bloating, vomiting and poor growth but celiac can also be silent, without evident symptoms. In a person with diabetes, erratic blood sugars that are hard to control can be a symptom of undiagnosed celiac disease.
Although type 1 diabetes is often diagnosed first, celiac disease may, in fact, be present first. Indeed, new studies suggest that inflammation and intestinal changes associated with celiac disease might promote autoimmunity, opening the way to the development of autoimmune diseases like type 1 diabetes. Intestinal permeability (or “leaky gut”) in celiac disease patients may trigger antigens to enter the bloodstream and lead to other autoimmune conditions.
“Could the development of celiac disease constitute an additional risk for developing type 1 diabetes, meaning that it would induce changes that put people more at risk for developing type 1 diabetes? Today we don’t have a definitive answer. But there are a number of observations that suggest that this may be the case,” says Bana Jabri, MD, PhD, a celiac disease researcher and professor of medicine, pathology and pediatrics at the University of Chicago Medical Center. “Some unpublished studies have suggested that changes in the gut and the microbiome may be associated with increasing autoimmunity. These studies have mainly been done in mice,” she says, stressing the critical need for more research, particularly studies in humans, to confirm these results.
“We need more studies, in humans, on the gut of type 1 diabetes patients to see if there’s evidence of inflammation. If this were proven, it would open the door for developing therapies in the gut, so that one could prevent the development of type 1 diabetes in at-risk patients.”
When people have diabetes and undiagnosed celiac disease, they may have fluctuations in blood sugar levels due to malabsorption issues. Their blood sugar may be difficult to control and they may have more episodes of hypoglycemia (low blood sugar). When they go on a gluten-free diet, their intestines heal, nutrients are absorbed better and blood sugars rise. Consequently, insulin doses need to be adjusted.
Many gluten-free foods have smaller serving sizes that are denser in carbohydrates and lower in fiber than their wheat-based counterparts. Also, many gluten-free foods use simple starches like white rice flour, tapioca starch and potato starch that can cause blood glucose to spike. So people with diabetes need to relearn how to count their carbs. They also need to check their blood sugar more often to find out how gluten-free foods affect their blood glucose, so they can adjust insulin timing and dosing. “Managing type 1 diabetes means juggling a lot of balls in the air at once. With a celiac diagnosis, you take away gluten and that changes the way sugar and food are being absorbed. So you have to adjust the insulin timing and dosing and rethink it again,” Philipson says.
The American Diabetes Association recommends that patients with type 1 diabetes be screened for celiac disease at onset of diabetes or if they exhibit gastrointestinal symptoms. Some endocrinologists screen patients for celiac more often—at diabetes onset, once a year for several years, and then every two to three years—since celiac can develop later in life. Diabetes patients are also periodically screened for thyroid and adrenal disease.
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