We’ve all heard of it, but do you even know what your thyroid does?
The thyroid gland is one of the most important organs in the human endocrine system. Hormones produced in the thyroid (T3 and T4) are released into the bloodstream and help regulate how the body uses and stores energy. When everything works as it should, thyroid hormone levels are tightly controlled by the pituitary gland in the brain. Loss of this control leads to thyroid hormone levels that are either too low (hypothyroidism) or too high (hyperthyroidism), and abnormal levels can have negative effects on the heart, bones, cholesterol levels, glycemic control, and a lot of other metabolic processes. Thyroid disease is actually fairly common in the general population (especially in women) and risk increases with age. Unfortunately, people living with diabetes have an increased risk of developing thyroid dysfunction.
Hypothyroidism is by far the most common thyroid disorder in adults, and Hashimoto’s disease is easily the most common cause of hypothyroidism. Hashimoto’s is an autoimmune disease in which the immune system attacks the thyroid gland and slowly kills it off over years or decades, leading to a decline in thyroid hormone levels. Symptoms of hypothyroidism may include fatigue, weight gain, intolerance to cold, constipation, dry skin and hair, muscle cramps, aches, decreased concentration, and depressed mood.
Hyperthyroidism from an overactive thyroid gland is much less common. Graves’ disease (another autoimmune disease) is the most frequent cause of hyperthyroidism. Symptoms may include fatigue, weight loss, heart palpitations, frequent stools, tremors, anxiety, irritability, sweating, intolerance to heat, and dry/irritated eyes. Many of the symptoms of thyroid dysfunction are what we call “nonspecific”, meaning that they could be caused by any number of diseases (like sleep apnea, depression, obesity, and poorly controlled diabetes) or even lifestyle issues (such as poor diet, lack of exercise, stress, etc). The thyroid gets a lot of blame, but sometimes it’s not the thyroid’s fault!
Diabetes and Thyroid Disease
Diabetes and thyroid disease are related in a number of ways. First, it has been shown that having one autoimmune disease increases the chance of developing another autoimmune disease. Therefore, people (especially women) living with type 1 diabetes have a higher rate of both Hashimoto’s and Graves’ disease compared to the general population. Second, there may be an association with type 2 diabetes and thyroid dysfunction, especially hypothyroidism. One study showed that people with low thyroid function were at a greater risk of progressing from prediabetes to type 2 diabetes. Finally, untreated hyperthyroidism generally leads to increased insulin requirements and worsened glycemic control in both type 1 and type 2 diabetes.
Screening and Treatment
Regular screening for thyroid dysfunction should be done in everyone with diabetes; roughly every 1-3 years in type 1 diabetes, and every 3-5 years in type 2 diabetes. The best way to test for abnormal thyroid function is to get a TSH level during a blood draw. If the TSH is normal, the thyroid is working well and no further testing is necessary in most cases. However, if the TSH is out of the normal range or the physician has a high suspicion for thyroid problems, other tests may be ordered including free T4, total T3, TPO antibody (associated with Hashimoto’s), TSI/TRAb (associated with Graves’), or thyroid imaging. If hypo- or hyperthyroidism is diagnosed, your physician should discuss treatment options with you or refer you to an endocrinologist for consultation. Hypothyroidism is treated by replacing the thyroid hormone, usually with a once-daily oral medication called levothyroxine. Treatment for hyperthyroidism depends on the exact cause, with options ranging from medications, to radioactive iodine therapy, to surgery. In both hypo- and hyperthyroidism, the TSH levels should be monitored during and after treatment to assure normal thyroid hormone levels are achieved and maintained. Regular testing of thyroid dysfunction is important for everyone with diabetes, but the good news is that treatment options are available, management of the condition is possible and getting your thyroid numbers in a normal range is very achievable.