The underappreciated but very important endocrine system is critical to regulating a number of vital organs, such as the pancreas and thyroid gland. When a person’s endocrine system malfunctions and the pancreas fails to produce adequate (or any) insulin, diabetes occurs. When that person is also dealing with thyroid problems, often manifesting as low amounts of thyroid hormone, resulting changes in insulin levels and overall changes in energy metabolism can make blood glucose control even more challenging.
“Unmanaged thyroid disease can have a significant impact on the overall management of diabetes,” said Noah Bloomgarden, MD, assistant professor of medicine in the department of endocrinology, diabetes and metabolism at Albert Einstein College of Medicine in New York City. “Thyroid disorders make it harder to manage your glucose levels if you already have diabetes.”
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An estimated 7% of the general population lives with some form of thyroid disease, which is second only to diabetes as the most common disorder of the endocrine system. Thyroid disorders are known to increase with age and are more common among women and those with other autoimmune disorders, explained Veronica Brady, PhD, MSN, CDE, assistant professor at the University of Texas Cizik School of Nursing in Houston. “People with a family history of thyroid disease are also at higher risk of developing problems with the thyroid gland.”
The prevalence of thyroid diseases among those with diabetes is two to three times higher than in those without diabetes. People with type 1 diabetes have a greater risk of developing autoimmune thyroid disorders and especially Hashimoto’s thyroiditis, which causes inflammation of the thyroid gland (a butterfly-shaped organ located in the lower neck). The association between type 2 diabetes and thyroid conditions is less common and not well understood, since type 2 diabetes is not a known autoimmune disease. “Both type 2 diabetes and thyroid disease are common disorders, but the specific relationship between them is less clear,” explained Melissa Young, PharmD, CDE, a clinical pharmacy specialist with the Department of Veterans Affairs office in Salt Lake City, Utah.
Hypothyroidism, the most common form of thyroid disease among those with diabetes, occurs when the thyroid gland doesn’t make enough hormone to help keep the body functioning normally. Hyperthyroidism, or levels of thyroid that are too high, “may be hard to distinguish from low blood glucose because both can cause sweating, tremors and irritability,” added Young.
Two thyroid conditions to know
Hypothyroidism occurs when the thyroid does not produce enough hormone to keep the body running smoothly. The most common cause of hypothyroidism is an autoimmune disorder called Hashimoto’s thyroiditis (also known as chronic lymphocytic thyroiditis), which is inflammation of the thyroid gland. The most common symptoms of hypothyroidism include fatigue, weight gain, constipation, increased sensitivity to cold, dry skin, depression and muscle aches.
Hyperthyroidism occurs when the thyroid is overactive and produces too much of a hormone called thyroxine. Too much thyroxine in the system can accelerate metabolism, causing unintentional weight loss, along with heartbeat irregularities, nervousness and tremors. The most common cause is Graves’ disease, an autoimmune disorder in which antibodies stimulate the thyroid to pro
Testing and treating
When signs and symptoms such as fatigue, weakness, weight gain or weight loss, dry hair, dry skin, sensitivity to cold, muscle cramps and constipation appear, that may indicate the thyroid gland is not functioning properly. That means it’s time to see a doctor and get tested for thyroid disease.
According to the American Thyroid Association, the most common test is the thyroid-stimulating hormone test (TSH). This is the most sensitive laboratory test to determine the presence of hypothyroidism or hyperthyroidism. The test, considered the most reliable and sensitive available, allows for both of these conditions to be diagnosed with certainty by measuring how much of the main thyroid hormone, known as thyroxine, is being made by the thyroid gland.
Contributing factors of thyroid disease
• Sex (women are seven to eight times more likely than men to have the condition)
• Age (it can occur even in children, but the risk is increased in those over 50)
• Genes (i.e. if family members have Hashimoto’s or other thyroid diseases)
• Presence of other autoimmune diseases (type 1 diabetes, rheumatoid arthritis, lupus, celiac disease, etc.)
• Previous thyroid surgery
• Too much or too little iodine
• Exposure of the neck to radiation
• Certain medications (e.g. lithium, amiodarone, interferon alpha, interleukin-2)
• Damage to the pituitary gland
Source: American Thyroid Association
If the test comes back with abnormal results, your doctor may order another test — called T4 — to determine the underlying cause or problem affecting your thyroid gland. “This is an important test to assess thyroid function prior to starting any medications,” stated Young.
The standard of care for treating hypothyroidism is a synthetic version of T4 called levothyroxine, which is typically used as the first treatment. This thyroid-replacement hormone is available in brand-name (Synthroid) and generic versions.
Adding a thyroid replacement medication, such as levothyroxine, may lead to changes in a person’s blood glucose control. “As thyroid hormone is supplemented, metabolism increases, which can include metabolism of blood-sugar-lowering medications such as insulin,” said Young. “If this happens, it can be managed with blood glucose monitoring and medication adjustments, especially during the time when thyroid medications are first initiated.”
Hyperthyroidism is often treated with a medication called methimazole, which works by making it harder for the body to make thyroid hormones. Surgical removal of the thyroid gland or radioactive iodine are other treatment options. If the gland is surgically removed, patients must take thyroid replacement hormone daily on an empty stomach at doses needed to maintain normal thyroid function. Ann-Marie Kloogh, who lives with type 2 diabetes in Salt Lake City, had her thyroid removed in 2018. “I take my thyroid replacement medication daily and have felt a lot better since the surgery.”
Between diabetes and thyroid medications, it can be a lot to keep track of, but it’s important to take them as directed and to see your doctor for regular monitoring. “These medications can be life-saving, but sometimes medications have side effects, so you have to share any changes in your health status with your doctors,” said Bloomgarden. “One of the biggest mistakes is to think that doctors will not listen or care. We want to hear about any changes so we can adjust medications and help you better manage your disease.”
Want to learn more about diabetes and thyroid health? Read “Thyroid Disorders and Diabetes,” “Diabetes and Your Thyroid” and “Eating for a Healthy Thyroid.”