Thyroid Disease and Diabetes

It's not uncommon for someone to have both thyroid disease and diabetes. In fact, if you have type 1 diabetes, type 2 diabetes, insulin resistance, or metabolic syndrome, your risk of developing thyroid disease is increased.

On the flip side, thyroid disease increases your risk of developing metabolic syndrome or type 2 diabetes. The association is even stronger if you are overweight or obese.

thyroid disease and diabetes
Verywell / Hilary Allison

This article helps explain how thyroid disease and diabetes are related. It also offers insights on how to avoid diabetes if you have thyroid disease and vice versa.

Thyroid Disease and Blood Sugar

The thyroid gland, the butterfly-shaped organ at the base of the neck, plays a major role in regulating many of your body's functions, including metabolism (how your body uses energy).

Because thyroid disease interferes with metabolism, blood sugar (glucose) that would otherwise be used for energy can instead start to accumulate. This increases your risk of diabetes, and it makes it harder to manage your blood sugar if you already have diabetes.

Hyperthyroidism (an overactive thyroid) is closely linked with hyperglycemia (high blood sugar).

Hyperglycemia caused by thyroid disease can also contribute to metabolic syndrome. Metabolic syndrome is a cluster of five conditions—high glucose, high blood pressure, high triglycerides, low HDL cholesterol, and a large waist—that increases the risk of heart disease, diabetes, and stroke.

Untreated metabolic syndrome can progress to type 2 diabetes.


The thyroid gland helps regulate metabolism (the conversion of food to energy). Thyroid disease can disrupt metabolism, allowing blood sugar levels to rise. High blood sugar levels increase the risk of type 2 diabetes.

Thyroid Disease and Insulin

Thyroid disease can also interfere with the production of insulin. Insulin makes it possible for cells to use glucose for energy. This lowers blood sugar.

Because hyperthyroidism increases metabolism, insulin is eliminated from the body faster than usual. This can lead to high blood sugar and an increased risk of type 2 diabetes. People with diabetes who need insulin shots may also find themselves needing higher doses.

On the flip side, hypothyroidism (an underactive thyroid) decreases metabolism. When this happens, insulin can linger, causing blood sugar to drop (hypoglycemia). For people on diabetes medications, the drop can sometimes be extreme, leading to dizziness, disorientation, and unconsciousness.


Thyroid disease can affect insulin levels. Because hyperthyroidism increases metabolism, insulin is eliminated faster, causing blood sugar levels to rise. This can increase the risk of diabetes or make diabetes harder to control. Hypothyroidism can lead to low blood sugar.

Other Connections

In addition to problems with glucose metabolism and insulin production, there are several other links between thyroid disease and diabetes.

Autoimmune Disease

Type 1 diabetes is an autoimmune disease in which the immune system attacks the cells that make insulin. There are certain forms of thyroid disease, called Hashimoto's thyroiditis and Graves' disease, that are also autoimmune.

Hashimoto's thyroiditis is the most common cause of hypothyroidism in the United States. Studies suggest that most people with type 1 diabetes will eventually develop Hashimoto's disease.

Graves' disease, on the other hand, causes hyperthyroidism. Around 10% of people with type 1 diabetes will develop Graves' disease.

Hypothalamic-Pituitary-Adrenal Axis

Thyroid hormones and insulin are both influenced by three organs that work together: the hypothalamus of the brain, the pituitary gland, and the adrenal glands.

Referred to as the hypothalamic-pituitary-adrenal axis (HPA axis), these organs send signals back and forth to each other and together control the body's response to stress. They do this by adjusting levels of the stress hormone cortisol.

Problems with any of the organs in the HPA axis can affect how much or how little cortisol is produced. High cortisol levels can lead to hyperglycemia. Low cortisol levels can lead to hypoglycemia.


Type 1 diabetes, an autoimmune form of diabetes, often occurs alongside autoimmune thyroid disease. Problems with the HPA axis, which produces the stress hormone cortisol, can lead to abnormal insulin and thyroid hormone levels.

Prevention and Management

If you have been diagnosed with either thyroid disease or diabetes, achieving and maintaining your ideal weight is one of the best ways to prevent the other condition. Keeping your blood sugar or thyroid hormones under control can also help.

If you have insulin resistance, in which the body doesn't respond to insulin as it should, thyroid disease can make your blood sugar harder to control. By managing insulin resistance with medications, diet, and exercise, you may be able to avoid diabetes as well as complications of thyroid disease.

By managing hyperthyroidism with medications, diet, and exercise, you may also reduce your risk of type 2 diabetes.


If you have diabetes or thyroid disease, maintaining an ideal weight may help you avoid getting the other condition. Properly managing your blood sugar or thyroid hormone can also help.


Diabetes and thyroid disease are closely linked. If you have hyperthyroidism, your insulin levels can drop and your blood sugar can rise, increasing the risk of diabetes. If you have hypothyroidism, the opposite can occur and lead to bouts of low blood sugar.

On the flip side, type 1 diabetes (an autoimmune form of diabetes) can increase the risk of Hashimoto's thyroiditis and Graves' disease (autoimmune forms of thyroid disease). Problems with the HPA axis, a group of organs that produce the stress hormone cortisol, can also have a negative effect on insulin and thyroid hormone levels.

If you have diabetes or thyroid disease, properly managing your condition and maintaining an ideal weight may reduce your risk of developing the other condition.

A Word From Verywell

Because there is a significant risk of thyroid problems in people with type 1 diabetes, the American Diabetes Association (ADA) recommends that everyone diagnosed with type 1 diabetes be tested for hypothyroidism soon after their diagnosis.

Even if the results are normal, the ADA recommends follow-up tests at least once every two years.

Frequently Asked Questions

  • Is PCOS linked to thyroid disease or diabetes?

    Yes, polycystic ovarian syndrome (PCOS) has been linked to both thyroid disease and diabetes. Autoimmune thyroid disease has been reported in up to 40% of women with PCOS. More than half of the women with PCOS will develop diabetes by age 40.

  • What are some complications of uncontrolled diabetes?

    People with diabetes are at greater risk of infections and skin conditions. Diabetes can damage blood vessels, impacting multiple organs including the heart, kidneys, bladder, sexual organs, and eyes. Uncontrolled blood sugar can also cause gum disease and diabetic neuropathy (nerve pain).

10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  7. American Diabetes Association. Children and adolescents. In: 2016 Standards of Medical Care in Diabetes. Diabetes Care. 2016;39:S13-22. doi:10.2337/dc16-S014

  8. Romitti M, Fabris VC, Ziegelmann PK, Maia AL, Spritzer PM. Association between PCOS and autoimmune thyroid disease: a systematic review and meta-analysisEndocrine Connections. 2018;7(11):1158-1167. doi:10.1530/EC-18-0309

  9. Centers for Disease Control and Prevention. PCOS (polycystic ovary syndrome) and diabetes.

  10. MedlinePlus. Diabetes complications.

Additional Reading

By Gary Gilles
Gary Gilles is a licensed clinical professional counselor (LCPC) who has written about type 1 diabetes and served as a diabetes counselor. He began writing about diabetes after his son's diagnosis as an infant.