How Thyroid Dysfunction May Lead To Diabetes

If your doctor diagnoses you with a thyroid condition, know that you are not alone. At least 12% of Americans will develop thyroid dysfunction in their lifetime, according to the American Thyroid Association. Women are more at risk than men, with one in eight women experiencing a thyroid problem at some point in her life.

Considering its small size, it's amazing how vital the thyroid is in supporting our overall health. The thyroid — a roughly two-inch-long endocrine gland located at the front of your lower neck that is shaped like a butterfly — produces a hormone that has an impact on almost every cell in your body. For one, the thyroid plays a pivotal role in regulating the body's metabolism. Weill Cornell Medicine also explains that the thyroid impacts bodily functions, such as heart rate, hair growth, and digestion.

The thyroid has some interesting history associated with it. As far back as 2697 B.C., there is evidence that the Chinese used iodine as a method for treating goiters, an irregular enlargement of the thyroid gland often caused by iodine deficiency. Also, the word "thyroid" has its origins in the ancient Greek word "thyra," which means "door," or the stone set against a door to keep it closed. In the 17th century, the English physician Thomas Wharton is believed to have conceived the word "thyroid." Scientific research associated with thyroid conditions later accelerated during the 20th century and still continues today.

How the thyroid gland works

When everything is functioning correctly, the thyroid gland is a well-oiled machine. The process starts with the hypothalamus, a control center of sorts that is located deep within your brain, linking your nervous system and endocrine system. One function of the hypothalamus is to produce thyrotropin-releasing hormone (TRH), a chemical messenger that tells the pituitary gland to release thyroid-stimulating hormone (TSH). TSH then travels through your bloodstream to the thyroid gland, where it stimulates the production of two hormones — triiodothyronine (T3) and thyroxine (T4), per Endocrineweb.

According to the Cleveland Clinic, T3 and T4 are critical for regulating your body's metabolism and growth. They control everything from your heart rate to your digestion. Depending on the levels of T3 and T4 in your bloodstream, your pituitary gland will either increase or decrease thyroid stimulation hormone (TSH), which consequently influences the thyroid to either speed up or slow down the production of T3 and T4.

When the thyroid gland isn't performing properly, it can cause a whole host of problems. For example, hypothyroidism — or underactive thyroid — occurs when the thyroid gland doesn't produce enough hormones. This malfunction can lead to fatigue, weight gain, thinning hair, slow heart rate (bradycardia), and depression. On the other hand,  hyperthyroidism — or overactive thyroid — occurs when the thyroid gland produces too many hormones, which can cause symptoms, such as weight loss, anxiety, rapid heartbeat, or a goiter, among other issues.

Thyroid disease and diabetes

Thyroid issues and diabetes may seem like two entirely different health conditions, but there's actually a significant connection between them. Understanding this connection can help you better manage your health and well-being if you have or are at risk of developing diabetes.

For instance, research shows that thyroid dysfunction — such as hypothyroidism — can increase your risk of developing diabetes. According to a 2016 study published in BMC Medicine, individuals with prediabetes and hypothyroidism are up to two times more likely to develop diabetes than those without the condition. Similarly, individuals with diabetes are at a higher risk of developing thyroid problems, with autoimmune thyroid dysfunction occurring in up to 30% of adults with type 1 diabetes, according to a 2019 study published in Endocrine Reviews.

The connection between the two comes down to how the hormones in your body interact. Both the thyroid gland and the pancreas — which produces the hormone insulin to regulate your blood sugar — are part of the endocrine system. When there's an imbalance in one gland, it can affect the function of other glands. For example, when the thyroid gland isn't producing enough hormones, it can cause insulin resistance — a hallmark of type 2 diabetes, per MedicalNewsToday.

The relationship between diabetes and the thyroid is complex. If you have diabetes or thyroid problems, it's important to have regular check-ups with your doctor to monitor your health. Managing your blood sugar and thyroid hormone levels can help prevent complications down the road.