Diabetes and Associated Autoimmune Diseases
I thought we would delve into more biology this week since we have discussed many psychosocial topics lately. A diagnosis of type 1 diabetes is usually associated with autoimmunity. (However, not all people with type 1 diabetes have evidence of autoimmunity.) What exactly does autoimmunity imply? Autoimmunity means that your own cells that are usually associated with fighting foreign visitors to your body (viruses, bacteria, etc.) actually attack other cells in your body because they were somehow fooled into thinking they were not you. This occurs because there may be similar structures on the molecular level between your own cells and the offending ones, which prompts an attack by your cells. As a result of this autoimmune attack, innocent victims may include organs such as your pancreas (diabetes), thyroid (autoimmune thyroiditis), joints (juvenile rheumatoid arthritis), intestines (celiac disease), and (rarely) adrenal glands (Addison’s Disease).
These diseases have an association with a certain genetic inheritance pattern on chromosome 6 named the Histocompatibility Locus (or HLA locus). Both of your parents contribute to your genetic make-up. Having this particular inheritance pattern does not necessarily mean that you will contract one of these autoimmune diseases. It means that you have an increased chance if something else triggers the disease process. It is therefore necessary to have another intruder (virus, bacteria or unknown offender) to start the attack on these organs by your own killer cells. This autoimmune process that damages your organs may take a long time or it may occur rapidly.
In type 1 diabetes, Beta cells in the pancreatic islets of langerhans are attacked, resulting in the loss of insulin produced by these cells and the development of high blood sugars and the ensuing symptoms of which you are very well aware. We detect evidence of this attack with elevated GAD-65 antibodies (and others) that are associated with pancreatic Beta cells. Positive GAD-65 antibodies assist your healthcare team in diagnosing type 1 diabetes. Some teens may develop a combination of type 1 diabetes (positive GAD-65 antibodies) and signs of type 2 diabetes (high blood sugars, obesity, dark pigmentation on the neck called acanthosis nigricans, in association with a strong family history of type 2 diabetes).
Autoimmune thyroiditis occurs when killer cells attack the thyroid gland, resulting in either too little or too much production of thyroid hormone. Your thyroid may enlarge, which is evidence that it is trying hard to make enough thyroid hormone. Your diabetes team measures the thyroid hormone level (free T4) and thyroid stimulating hormone (TSH) to figure out if you are making too much or too little thyroid hormone. The two most common forms of autoimmune thyroiditis are called Hashimoto’s thyroiditis (too little thyroid hormone and is usually associated with a need to give thyroid hormone orally with Synthroid or L-thyroxine) and Graves Disease (too much thyroid hormone and medications or treatments are provided to decrease the amount of produced thyroid hormone). Elevated thyroid antibodies provide evidence of autoimmunity and are commonly measured to help identify autoimmune thyroiditis.
Celiac disease is an intolerance to wheat or gluten products. In celiac disease, cells of your small intestine are attacked by killer cells, resulting in a decreased ability to absorb foods with gluten or wheat. Celiac disease is often without symptoms, but sometimes healthcare providers are alerted to the disease by a patient’s failure to grow in height or weight, or issues with digestion or menstruation in women. Physicians perform bloodtests called anti-serum tissue transglutaminase levels or anti-endomysial antibodies to detect the possibility of celiac disease. Definitive diagnosis is made by intestinal biopsy and treatment is with a “gluten-free” diet.
Juvenile rheumatoid arthritis (JRA) is a disease that can attack the small or large joints of your body. Symptoms include pain, swelling, warmth, or redness in one or several joints. Rheumatologists use various medications to alleviate symptoms. Once again, lab tests including antibody determinations help to diagnosis this autoimmune disease.
Lastly, and most rarely, Addison’s disease may occur. The adrenal glands are attacked, which results in the inability to make corticosteroid hormones that work to help you fight infections and manage stress. (John F. Kennedy was afflicted with Addison’s disease and was treated with steroid medication before and during his presidency. Many believe that Jane Austen, author of Pride and Prejudice and Emma, suffered from Addison’s Disease as well.) Anti-adrenal antibodies are measured along with other hormones to help diagnose this rare condition.
Your healthcare team will usually perform routine laboratory work to check for the possibility of several of the more common autoimmune diseases associated with diabetes, such as autoimmune thyroiditis and celiac disease. Physicians rarely test for juvenile rheumatoid arthritis or Addison’s disease unless they are concerned that you may be exhibiting the appropriate symptoms. At your next appointment, if you see the following tests written on your laboratory slip, TSH, antithyroid antibodies, free T4, serum tissue transglutaminase, anti-endomysial antibodies, etc., you will know exactly why.
If you have any questions in regard to the autoimmune diseases associated with diabetes, please comment below. I am happy to give more details.
Fran Cogen, M.D., C.D.E., is the director of the Childhood and Adolescent Diabetes Program at Children’s National Health System. She wrote about diabetes for HealthCentral.