The link between celiac disease and type 1 diabetes mellitus is well known. There are different types of diabetes mellitus, but type 1 and celiac disease have a lot in common. They share some of the same genes, are activated by environmental triggers, have increased risk for associated autoimmune diseases and include symptoms that mimic other diseases. Also, self-management is recommended as a best practice in the treatment of both diseases. The purpose of this dialogue is to increase awareness about diabetes mellitus and celiac disease.
Diabetes is defined as any disorder with frequent urination (polyuria) while “mellitus” means a chronic syndrome of impaired carbohydrate, protein and lipid (fat) metabolism due to insufficient insulin. The most common forms of diabetes mellitus are type 1, type 2 and gestational. Over time, the term “diabetes mellitus” has been shortened to simply “diabetes”.
Type 1 is sometimes called juvenile diabetes since it is most often diagnosed in children and young adults. Individuals with type 1 diabetes do not make enough or do not make any insulin. Insulin is a hormone produced in the body to break down food and beverages so they can be used for energy. Type 1 is also referred to as insulin-dependent diabetes since daily injections of insulin are required.
Only individuals with certain genes develop type 1 diabetes. However, not all individuals with these genes become type 1 diabetics. An environmental trigger is needed to activate type 1 diabetes. Unlike celiac disease where the environmental trigger has been identified (gluten), the environmental trigger for type 1 diabetes is unknown. Another feature shared by type 1 diabetes and celiac disease is the presence of autoantibodies in the blood of susceptible individuals. Autoantibodies are proteins that attack the body’s own tissue, and may be present for years before the disease is obvious. According to the American Diabetes Association, 5–10 percent of individuals with diabetes have type 1.
Type 2 is also known as insulin-resistant diabetes. Individuals with type 2 diabetes make insulin but cannot use it properly. The main role of insulin is to transport glucose into cells for energy production. When insulin receptors become “resistant,” the transportation of glucose into cells slows down or stops causing glucose levels in the blood to build up. The majority of individuals with diabetes have type 2.
Individuals can be genetically predisposed to type 2 diabetes, but these genes do not increase the risk of celiac disease. If an individual with celiac disease has type 2 diabetes, it is for the same reason as anyone in the general population. Diabetes experts think type 2 diabetes is associated with a Western lifestyle. Studies of ethnic groups (African Americans, Mexican Americans and Pima Indians) genetically predisposed to type 2 diabetes living in the United States have shown a higher rate of this disease than their counterparts living in non-Westernized areas. Besides genetic predisposition, being sedentary and/or obese increases the risk of type 2 diabetes.
Type 2 diabetes is treated with dietary and lifestyle changes. Sometimes oral medications are used, and on occasion individuals with type 2 diabetes may need insulin to control their blood glucose levels. Another way to improve blood glucose levels in obese individuals is to lose a modest amount of weight (7 percent of body weight).
As the term “gestational” suggests this type of diabetes happens in women who are pregnant and have never had diabetes. The exact cause of gestational diabetes is not known but one theory is that pregnant women become insulin resistant due to increased hormone levels. Gestational diabetes usually develops later in pregnancy and resolves once the pregnancy ends. It is estimated that 4 percent of pregnant women each year in the United States have gestational diabetes. Gestational diabetes is treated like type 2 with dietary modifications and increased physical activity.
Celiac disease and type 1 diabetes
Celiac disease and type 1 diabetes are genetically based disorders sharing similar genes (DQ2 and DQ8). Both diseases are immune-regulated and associated with autoimmune thyroiditis and rheumatoid arthritis. About 3.5 to 10 percent of individuals with celiac disease develop type 1 diabetes and visa versa. Screening for celiac disease or type 1 diabetes is recommended in individuals already diagnosed with either disorder. When individuals have both diseases, type 1 diabetes is usually diagnosed first. It has been speculated that symptoms of type 1 diabetes are more obvious and therefore easier to diagnose than those of celiac disease. Table 1 provides a comparison of common symptoms seen in undiagnosed celiac disease and type 1 diabetes.
Individuals with type 1 diabetes and undiagnosed celiac disease may experience unstable blood glucose levels, decreased insulin requirements, delayed gastric emptying, weight loss, growth failure (in children) and loss of bone density (osteopenia). Even after being diagnosed with celiac disease and starting a gluten-free, lifestyle symptoms may take up to a year to improve. Some type 1 diabetics with newly diagnosed celiac disease report problems with hypoglycemia, increased insulin needs and elevated hemoglobin A1C (glycosylated hemoglobin; measures average blood glucose over past 2-3 months) levels after beginning a gluten-free diet. These problems are thought to be due to improved absorption associated with healing in the gastrointestinal tract. They may also be linked to the type and density of carbohydrates found in gluten-free foods.
Medical nutrition therapy
Medical nutrition therapy and self-management are important components in the treatment of both celiac disease and type 1 diabetes. Selfmanagement allows development of an individualized care plan that can be adjusted as needed. There is no “one diet fits all” for either type 1 diabetes or celiac disease. Medical nutrition therapy for both diseases begins with a wellbalanced, nutritionally complete diet plan based on individual preferences and requirements. A meal plan for individuals with type 1 diabetes is designed to support healthy blood glucose levels. Meals and snacks should contain carbohydrates, proteins, and lipids. It is important to be consistent with serving sizes (portions) and eating times. Eating every 3–4 hours instead of once or twice a day makes it easier to control blood glucose levels.
Carbohydrates raise blood glucose levels, but not all carbohydrates raise blood glucose levels at the same rate. Factors such as gender, age, health status and activity determine individual carbohydrate requirements. To keep blood glucose levels within a healthy range, it is essential to track the amount (grams) of carbohydrates consumed during meals and snacks as well as a daily total. One way to do this is with “carb counting.” An understanding of different types of carbohydrates is necessary for carb counting to be effective. Carbohydrates are classified as sugars, starches and fiber. Table 2 provides information about carbohydrate classifications.
Sugars tend to raise blood glucose levels faster than starches and fiber. A tool for measuring how fast carbohydrate foods increase blood glucose levels is the glycemic index. Carbohydrate foods are classified as high, medium or low based on how they compare to the carbohydrate content of glucose or white bread. High glycemic index foods raise blood glucose levels faster than medium or low glycemic index foods. Balancing high glycemic foods with medium and low ones helps control blood glucose levels. The best way to find the carbohydrate content in a serving of food is by reading the nutrition label. Terms such as added sugar, complex carbohydrates, low or reducedcalorie sweeteners, sugar alcohols, and enriched, refined or whole grains can be found on nutrition labels, but the number to use for carb counting is “total carbohydrate.”
Adapting a type 1 diabetes meal plan to be gluten-free can be challenging. One step in transitioning to a gluten-free lifestyle is identifying gluten-free substitutes for glutencontaining foods. It should be noted that many gluten-free grains, flours, and foods contain more carbohydrate per serving than their gluten-containing counterparts resulting in smaller portions. Carb counting helps determine appropriate serving sizes. A new tool developed to provide carbohydrate content of gluten-free grains and flours can be found at the www.csaceliacs. org home page. Click on “Counting Gluten-Free Carbohydrates”.
Individuals with both diseases have to pay more attention and take extra care in maintaining a gluten-free type 1 diabetes meal plan. A dietitian skilled in type 1 diabetes or a certified diabetes educator (CDE) can help set up a meal plan and determine which tools and techniques will work best for an individual as well as adjust insulin dosages. It is easier to find a dietitian and/or CDE skilled in type 1 diabetes than one skilled in both type 1 diabetes and celiac disease. It may be necessary to partner with more than one dietitian when adapting a type 1 diabetes meal plan to include gluten-free. In addition to partnering with a skilled dietitian, it may be helpful to connect with a local CSA support group. CSA support group members are able to share experiences and successes in transitioning to a gluten-free lifestyle.
American Diabetes Association: http:// www.diabetes.org/
Bantle JP, Wylie-Rosett J, Albright AL, et al. Nutrition Recommendations and Interventions for Diabetes A position statement of the American Diabetes Association. Diabetes Care. 2008;31 (Suppl 1): S61-78.
Eyre S, Hinks A, Bowes J, et al. Overlapping genetic susceptibility variants between three autoimmune disorders: rheumatoid arthritis, type 1 diabetes and coeliac disease.
Arthritis Res Ther. 2010 Sep 20;12(5):R175.
Lavant, EH and Carlson, JA. Clin Chem Lab Med. 2009; 47(12):1489-95.2009. A new automated human leukocyte antigen genotyping strategy to identify DR-DQ risk alleles for celiac disease and type 1 diabetes mellitus.
Mayer-Davis EJ, Nichols M, Liese AD, et al. Dietary intake among youth with diabetes: the SEARCH for Diabetes in Youth Study. J Am Diet Assoc. 2006;106(5):689-97.
Narula P, Porter L, Langton J, et al. Gastrointestinal Symptoms in Children With Type 1 Diabetes Screened for Celiac Disease. Pediatrics. 2009; 124(3):e489-95.
Smyth DJ, Plagnol V, Walker NM, et al. Shared and distinct genetic variants in type 1 diabetes and celiac disease. N Engl J Med. 2008 Dec 25;359(26):2767-77.
Wheeler ML, Pi-Sunyer FX. Carbohydrate issues: type and amount. Am Diet Assoc. 2008; 108(4 Suppl 1):S34-9.