This is the first of a three-part series on celiac disease (CD) and type 1 diabetes (T1D), researched by Glu summer intern, Ryan Brennick (GluRyan).
Ever wonder what your providers are testing for when they are doing blood tests? Testing for celiac disease is popular for those with T1D, since symptoms often go unnoticed and those diagnosed with T1D may be at a higher risk.
What is Celiac Disease?
Celiac disease (CD) is an autoimmune disorder that causes damage to the villi of the small intestine. The villi of the small intestine are hair-like structures that are used to absorb nutrients as they travel through the digestive system. CD is generally discovered through symptoms of malabsorption including diarrhea, abdominal pain, iron deficiency, fatigue, and weight loss—although many people who have CD do not display symptoms. The cause of CD can be influenced by both genetic and environmental factors, similar to type 1 diabetes (T1D). The main treatment for CD is avoiding intake of gluten, a type of protein found in bread (described further below).
The prevalence of CD is between 1% and 2% of the total population of North America, South America, the Middle East, North Africa, and Asia. The disease incidence is between 10% and 15% for people with first-degree relatives who have it or for people with another autoimmune diseases (Yap, 2015). Recent studies have shown an increase in prevalence in certain parts of the world, particularly North America and Europe. Although diagnosed cases are increasing, there are estimates of extremely high numbers of undiagnosed cases as well.
The prevalence of people with a dual diagnosis of T1D and CD has been reported to be up to 20% depending on the location of the study. A recent Question of the Day answered by 524 people on Glu suggests that the co-prevalence of T1D and CD in our community is about 11 percent.
What is Gluten?
Gluten is a molecule that can be found in several grains such as barley, rye, and wheat. Gluten itself is made up of a mixture of proteins—more specifically glutenins and gliadins. Both of these proteins protect gluten in the gastrointestinal tract making it hard to digest. Within food, gluten affects the elasticity of dough and the chewiness of baked products. Baked products without gluten tend to be more breakable, crumbly or dry.
Gluten was introduced over ten thousand years ago, and gluten consumption is thought to have increased in the past half-century. This increase in gluten intake along with the introduction of a western diet in multiple countries is believed by many to be responsible for the rise of CD, although this relationship is still being investigated. The link between gluten and CD was established in the 1950s.
The treatment of CD is the elimination of gluten using a gluten-free diet. Those who follow a gluten-free diet must strictly eliminate gluten since even a small amount can prove harmful—in order for a food to be considered gluten-free there has to be less than 20 parts per million of gluten in the product (Lee, 2014).
What happens when someone with CD eats gluten?
CD is an autoimmune disorder; that is, the immune system attacks its own tissues. When someone with CD ingests gluten, the food is broken down as it moves through the digestive system. As it reaches the small intestine, the gluten molecules pass through the villi (the hair-like structures that absorb nutrients) as a part of digestion. In this stage the immune system recognizes the gluten molecules as potential pathogens and attacks them in the walls of the intestine. This is known as immune system reactivity.
The resulting damage to the villi of the small intestine due to the ingestion of gluten is not permanent. Since the small intestine is an organ, it is able to make new cells to replace the damaged cells once someone starts a gluten-free diet. It can take up to a month for a person with CD’s intestines to heal with a gluten-free diet.
Type 1 Diabetes and Celiac Disease
Even in people without CD, eating gluten can result in some immune system reactivity; interestingly, those with T1D show a greater immune response to gluten, even if they do not have CD (Auricchio, 2004; Troncone, 2003). Some researchers even theorize that eating gluten over time may be part of what ‘triggers’ the immune system to attack the pancreas, resulting in T1D; however, this relationship is not yet understood.
There is growing evidence to support the idea that patients with CD who follow a strict gluten-free diet may be protected against further diabetes-related complications. Studies have also found that T1D patients with CD have lower levels of retinopathy and cholesterol.
The association between celiac and T1D was established about 50 years ago. The dual diagnosis can be credited to overlapping genes (Bottini, 2004). Generally, people are diagnosed with T1D before they are diagnosed with CD; however, some people have been diagnosed with CD before T1D. It is difficult to screen for CD at diagnosis of T1D, as over ten percent of people eventually diagnosed with CD tested negative at the time of diagnosis of T1D, so rescreening later on is common.
Screening for Celiac Disease
The gold standard for diagnosing CD is an intestinal biopsy. However, because this kind of testing is considered to be invasive, people will typically get screened first by blood testing. The test detects antibodies that are produced by someone who has an immune response to gluten in food. Although the blood testing is generally accurate, intestinal biopsy makes the definitive diagnosis. Someone who does not eat gluten will not test positive since ingestion of gluten is necessary to cause the immune response and abnormal biopsy.
A recent question of the day showed that the majority of Glu users have not been screened for CD. Of those who were screened, the majority of them had the screening initiated by their diabetes care team.
Living with Type 1 and Celiac Disease
For some people, the gluten-free diet is not just a fad or lifestyle choice, it is a necessity. Managing diabetes and food intake is already hard enough, but having to eat gluten-free with type 1 diabetes can be extremely challenging. When deciding to eat out, someone with both T1D and CD may not have many options as some restaurants do not offer gluten-free foods or can cross-contaminate easily.
Do you, or does your child with T1D, also have celiac disease? How do you manage both diseases at the same time?
Auricchio, R.; Paparo, F.; Maglio, M.; Franzese, A.; Lombardi, F.; Valerio, G.; Nardone, G.;Percopo, S.; Greco, L.; Troncone, R. In vitro-deranged intestinal immune response to gliadin intype 1 diabetes. Diabetes 2004, 53, 1680–1683.
Bottini, N.; Musumeci, L.; Alonso, A.; Rahmouni, S.; Nika, K.; Rostamkhani, M.; MacMurray, J.;Meloni, G.F.; Lucarelli, P.; Pellecchia, M.; et al. A functional variant of lymphoid tyrosinephosphatase is associated with type I diabetes. Nat. Genet. 2004, 36, 337–338.
Lee, H.J.; Andreson, Z.; Ryu, D. Gluten free contamination in foods labeles “Gluten free” in United States. J. Food Prot. 2014, 77, 1830–1833.
Serena, G; Camhi, S; Sturgeon, C; Yan, S; Fasano, A. The role of gluten in celiac disease and type one diabetes. Nutrients. 2015, 7, 7143-7162.
Troncone, R.; Franzese, A.; Mazzarella, G.; Paparo, F.; Auricchio, R.; Coto, I.; Mayer, M.; Greco, L. Gluten sensitivity in a subset of children with insulin dependent diabetes mellitus.Am. J. Gastroenterol. 2003, 98, 590–595.
Yap, T.W.; Chan, W.K.; Leow, A.H.; Azmi, A.N.; Loke, M.F.; Vadivelu, J.; Goh, K.L. Prevalence of serum celiac antibodies in a multiracial Asian population—A first study in the young Asian adult population of Malaysia. PLoS ONE 2015, 10, e0121908.