Type 1 diabetes and thyroid eye disease (TED) are both autoimmune diseases. They occur when the body’s immune system mistakenly attacks its own cells. In type 1 diabetes, this occurs mostly in the pancreas, while in Graves’ disease (the main cause of thyroid eye disease), this occurs in the thyroid. Although the two conditions affect different body parts, they’re more closely related than one might think.

This article explains the connection between these two autoimmune conditions and what to do if you think you have symptoms of thyroid disease.

What Is an Autoimmune Disorder?

When the immune system malfunctions, it can lead to an autoimmune response — where a person’s own immune cells (antibodies) attack and destroy other cells in their body. There are more than 80 different autoimmune diseases affecting as many as 50 million Americans.

Certain people are more at risk for autoimmune diseases. Eighty percent of people living with autoimmune conditions are female. Thyroid eye disease is more common in women, according to Stanford Medicine. Males, however, tend to have more severe TED, according to Missouri Medicine. People with a family history are more likely to get autoimmune disease. People of certain races and ethnicities are more prone to different conditions.

Type 1 Diabetes

In type 1 diabetes, the immune system specifically attacks the beta cells in the pancreas that create insulin. When you have no insulin, your body can’t regulate blood glucose (sugar) levels. Most cases of type 1 diabetes are diagnosed in people during their childhood and adolescence.

Symptoms of type 1 diabetes include:

• Extreme thirst and hunger
• Frequent urination (which can manifest as bed-wetting in children)
• Weight loss
• Fatigue
• Vision changes

Thyroid Eye Disease

Thyroid eye disease causes inflammation and damage to the tissues around the eyes. Symptoms of TED include:

• Bulging eyes
• Double vision
• Eye pain
• Difficulty closing the eyes

TED is usually the result of Graves’ disease. Graves’ disease is a type of hyperthyroidism (overactive thyroid). It occurs when the immune system produces antibodies that cause the thyroid gland to overproduce thyroid hormones.

Symptoms of Graves’ include:

• Weight loss
• Rapid heartbeat
• Anxiety

Some people develop TED without Graves’ disease. The same antibodies that target the thyroid gland can attack the tissues around the eyes, leading to TED.

The Risk for Graves’ and TED in Type 1 Diabetes

People with type 1 diabetes have a higher chance of developing autoimmune diseases of other endocrine glands in the body, such as the thyroid. The risk of Graves’ is higher in people with type 1 diabetes than in people without the condition.

One study found that one quarter of people with type 1 diabetes had antibodies against the thyroid and that 4.1 percent had developed Graves’ disease. The exact reason for this remains unclear, but genetics and similar autoimmune pathways likely play a significant role.

Genetic Causes

Autoimmune polyendocrine syndromes (APS) tie together thyroid disease and type 1 diabetes. These rare syndromes (groups of symptoms) are called autoimmune polyendocrine syndromes. APS type 2 consists of adrenal insufficiency (Addison’s disease), thyroid dysfunction, and type 1 diabetes. APS type 2 usually involves hypothyroidism (underactive thyroid), which usually doesn’t cause thyroid eye disease. However, this syndrome may be a rare reason for someone to have both thyroid eye disease and type 1 diabetes.

Living With Both Conditions

A large United States-based study of thyroid eye disease in people with and without diabetes showed differences in how each group experiences TED:

• Age of diagnosis — People with diabetes were usually diagnosed later in life with TED than people without diabetes.
• Symptoms — People with diabetes and TED had higher rates of strabismus (crossed eyes) and diplopia (double vision) than people who had TED without diabetes.
• Complications — TED was more likely to cause sight problems in people with diabetes than without diabetes, probably because diabetes already can cause damage to the optic nerve.

When To Seek Medical Advice

If you’re living with type 1 diabetes but begin to experience symptoms such as weight loss, palpitations, or vision changes, contact your primary care doctor or endocrinologist. They can test your thyroid hormone and thyroid stimulating hormone (TSH) levels through a simple blood test to see how your thyroid is functioning. Early detection of thyroid problems can help prevent complications and prevent complications such as TED from worsening.

Treatment for Graves’ Disease and TED

The right treatment for you will depend on the severity of your condition and other factors. For Graves’ disease, common treatments include:

• Antithyroid medications, such as methimazole or propylthiouracil, to stop the production of thyroid hormones
• Radioactive iodine therapy to destroy the overactive thyroid cells
• Thyroid surgery (if other treatments are ineffective or symptoms are severe)

Treating Graves’ may help to stop TED from worsening, but it can’t reverse damage done to the eye and surrounding tissue.

Treatments for TED may include:

• Corticosteroids to reduce swelling (though steroids will raise a person’s blood glucose levels, an important consideration for people living with diabetes)
• Teprotumumab (Tepezza), an infused medication
• Lubricating eye drops to relieve dryness
• Surgical procedures

Treating Both Diabetes and Thyroid Disease

Having thyroid disease can make managing your diabetes more challenging. Your endocrinologist must carefully balance treatment for type 1 diabetes, thyroid eye disease, and hyperthyroidism. It is important to follow your treatment plan and report any new symptoms to your doctor.

Talk With Others Who Understand

On myT1Dteam, the social network for people with type 1 diabetes and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with type 1 diabetes.

Are you living with type 1 diabetes or thyroid eye disease? What tips do you have for others living with chronic autoimmune diseases? How do you make sure you get the health care you need to best manage your well-being? Share your experience in the comments below, or start a conversation by posting on your Activities page.