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.