T1D & Thyroid Diseases


Editor’s Note: This content has been verified by Marina Basina, MD, a clinical associate professor at Stanford University. She’s a clinical endocrinologist and researcher with a focus on diabetes management and diabetes technology. Dr. Basina is an active member of multiple medical advisory boards and community diabetes organizations, and she is on the Beyond Type 1 Science Advisory Council. 

What are thyroid diseases?

The two most common thyroid diseases that co-occur with type 1 diabetes are Hashimoto’s or hypothyroidism and Graves or hyperthyroidism. The estimated prevalence of hypothyroidism due to Hashimoto’s thyroiditis ranges from 4 to 19 percent of people with type 1 diabetes and 2 to 4 percent have Graves or hyperthyroidism in addition to type 1 diabetes. 

Both of these diseases affect the thyroid, an endocrine gland, that involves the production of thyroid hormones and therefore regulates many metabolic processes. The thyroid gland is in the front of the neck and shaped like a butterfly and releases the thyroid hormone into the bloodstream. It’s function is regulated by a feedback loop that involves the brain; when thyroid hormone is low in the bloodstream, the brain releases thyroid stimulating hormone (TSH) into the bloodstream which, true to its name, stimulates the thyroid gland to release thyroid hormone.

Hashimoto’s disease

In Hashimoto’s thyroiditis, the immune system attacks the thyroid directly. Because it is being attacked, the thyroid may be compromised and becomes unable to release sufficient the thyroid hormone. This can cause hypothyroidism, which is also known as an under-active thyroid. Women are eight times more likely than men to develop Hashimoto’s, and most commonly presents between the ages of 40 and 60, frequently earlier in individuals with type 1 diabetes.

Signs and symptoms of hypothyroidism:

  • Weight gain
  • Goiter, or enlarged thyroid, which may cause a feeling of fullness in the throat
  • Constipation
  • Memory fog
  • Bradycardia
  • Hair loss
  • Menstrual irregularity, especially heavy periods and infertility
  • Depression
  • Cold sensitivity
  • Muscle pain
  • Lethargy in more severe cases

Getting a Diagnosis

In order to diagnose hypothyroidism due to Hashimoto’s, doctors will do a physical exam and order one or more blood tests including thyroid peroxidase antibody (TPO). If TPO is elevated and the thyroid hormone is normal, you do not currently have hypothyroidism, but you are at a high risk of developing hypothyroidism. 


The treatment of Hashimoto’s thyroiditis depends on whether or not you have developed hyperthyroidism. If you have not, the doctor will probably choose to simply monitor you. However, if Hashimoto’s has lead to hypothyroidism, you will need to replace the thyroid hormone that your body is no longer able to make by taking levothyroxine which is taken orally, usually in the morning. Your doctor will also ask you to complete a blood test every six to eight weeks to make sure that your dose of levothyroxine is appropriate. 

Graves’ disease

Like Hashimoto’s, Graves’ is also an autoimmune disorder that causes the immune system to attack the thyroid. However, in people with Graves’ disease, the immune system is tricked into making antibodies that bind to the receptors on the thyroid’s cells and over-stimulate the thyroid cells. Basically, this means that the thyroid overproduces the thyroid hormone. This means that Graves’ disease leads to hyperthyroidism, which is simply an overactive thyroid. Also like Hashimoto’s, Graves’ affects eight times more women than men.

Signs and Symptoms:

  • Weight loss
  • Tachycardia
  • Irritability
  • Lethargy or weakness
  • Goiter, or enlarged thyroid, which may cause a feeling of fullness in the throat
  • Heat intolerance
  • Nervousness
  • Diarrhea
  • Trembling
  • Insomnia

Getting a Diagnosis

In order to diagnose you with Graves’ disease, your doctor will likely perform a physical exam and ask you to do a blood test. If the blood tests come back inconclusive, your doctor may also ask you to order further tests to be performed.


The most common form of treatment in the United States is radioiodine therapy. This involves taking radioactive iodine orally, which slowly destroys the thyroid hormone-producing cells in the thyroid. However, most people who do radioactive iodine treatment develop hypothyroidism because they have effectively destroyed the thyroid’s ability to produce any of the hormone. Hypothyroidism is easier to manage and also has fewer long-term health complications.

Other treatments for Graves’ disease are medicines such as beta blockers and antithyroid medicines, which are becoming an increasingly popular method of management. Beta blockers work by targeting the symptoms of hyperthyroidism, and antithyroid medicines work by reducing the amount of thyroid hormone that the thyroid produces. Finally, some elect to simply have their thyroid removed, which, like radioiodine therapy, leads to hypothyroidism.

Read about other autoimmune diseases.

WRITTEN BY BT1 Editorial Team, POSTED 05/10/18, UPDATED 12/31/22

This piece was authored collaboratively by the Beyond Type 1 Editorial Team.