Like type 1 diabetes, Hashimoto’s disease is an autoimmune condition. Autoimmune diseases happen when the body’s immune system attacks healthy tissues. Studies show that having one autoimmune disease means you’re more likely to get another.

If you have type 1 diabetes, it’s smart to get familiar with other autoimmune disorders, like Hashimoto’s disease, so you can spot the early signs of a potential problem.

What Is Hashimoto’s Disease?

In Hashimoto’s disease, also called Hashimoto’s thyroiditis, the immune system attacks the thyroid gland. Thyroid cells get destroyed, leading to hypothyroidism (low thyroid hormone levels). The thyroid makes hormones that affect many systems throughout the body, so people with Hashimoto’s need medication to bring their thyroid hormone levels back up to normal.

It takes time for the symptoms of Hashimoto’s to develop. Symptoms may include:

• Cold sensitivity
• Constipation
• Depression
• Dry skin
• Irregular periods
• Joint problems
• Memory problems
• Muscle weakness, pain, and stiffness
• Sleepiness and fatigue
• Trouble concentrating

Many of these symptoms are nonspecific (can have more than one cause), so it can take a long time, sometimes even years, for Hashimoto’s disease to be diagnosed. That’s why screening is important.

In addition, there are some physical symptoms of Hashimoto’s disease, such as a puffy face, goiter (a swollen thyroid gland), hair loss, an enlarged tongue, and brittle nails. These symptoms usually appear later, when the hypothyroidism is severe.

Hashimoto’s disease usually shows up during middle age, and women are at higher risk than men, according to Mayo Clinic. However, men can also develop the condition, and it may strike at any stage of life. A family history of thyroid problems, consuming too much iodine, and exposure to radiation may trigger Hashimoto’s in people who are already at risk.

If left untreated, Hashimoto’s can be dangerous. It can lead to heart problems, infertility, and a life-threatening condition called myxedema. This rare medical emergency occurs when exposure to a trigger, such as cold temperatures or an infection, causes a coma.

Does Diabetes Increase the Risk of Hashimoto’s Disease?

Hashimoto’s disease is the most common co-occurring autoimmune disease in people with type 1 diabetes. Study findings differ but suggest that about 15 percent to 30 percent of people with type 1 diabetes have Hashimoto’s disease, compared with about 2 percent of the general population.

Although most people get diagnosed with Hashimoto’s disease between ages 40 and 60, those with type 1 diabetes are more likely to develop it at a younger age.

People with type 1 diabetes also have an increased risk of other autoimmune thyroid diseases. Graves’ disease is a form of hyperthyroidism with the opposite effects of Hashimoto’s disease and is much less common. In Graves’ disease, the immune system overstimulates the thyroid gland. As a result, people have too much thyroid hormone and end up with symptoms like weight loss, heat intolerance, and restlessness. They can also develop thyroid eye disease.

How Is Hashimoto’s Disease Diagnosed and Treated?

If you suspect that you have a thyroid disorder, talk with your health care provider. Your doctor can check your thyroid function by screening your blood for thyroid- stimulating hormone (TSH) and thyroxine or thyroid hormone (T-4). High TSH and low T-4 levels are signs of hypothyroidism.

Thyroid antibody tests offer a more targeted way to determine if hypothyroidism is caused by Hashimoto’s disease or something else. Hashimoto’s is linked with specific antibodies in the immune system, including thyroglobulin and thyroid peroxidase antibodies. Finding these antibodies in your blood helps explain the root cause of thyroid dysfunction.

Mild cases of Hashimoto’s disease may need only monitoring. However, people with Hashimoto’s usually need hormone replacement therapy as an ongoing treatment for life.

Levothyroxine (Synthroid), a synthetic form of thyroid hormone, is a pill that boosts T-4 levels. In some cases, other forms of synthetic thyroid hormones are also prescribed. It takes time for your body to adjust to the medication. You’ll need to follow up and test your blood every six to 10 weeks to ensure the right dosage.

Hashimoto’s disease doesn’t necessarily interfere with type 1 diabetes treatment or increase the chances of complications that affect life expectancy with diabetes. However, anytime you have another health condition on top of type 1 diabetes, you have to watch out for potential issues. Make sure your health care providers know about any other treatments and conditions you have.

How Do Diabetes and Hashimoto’s Affect Heart Health?

Cardiovascular disease is the leading cause of death around the world. The biggest threats are heart attack and stroke. Both type 1 diabetes and Hashimoto’s disease raise the risk of specific heart problems, so it’s critical to pay attention to heart health when you have these two conditions.

Type 1 diabetes is a big risk factor for heart failure. Some studies suggest that people with type 1 diabetes are four times more likely to be hospitalized for heart failure than those without diabetes. Chronic hyperglycemia (high blood sugar) promotes heart failure, oxidative damage, and inflammation. Keeping your numbers under control can help protect your heart. Insulin therapy that achieves hemoglobin A1c levels as close to normal as possible significantly lowers heart failure and overall cardiovascular disease deaths.

Additionally, thyroid hormones directly affect the heart. Hypothyroidism in conditions like Hashimoto’s disease can cause high blood pressure and cholesterol levels and raise the risk of heart failure. Treating hypothyroidism helps, but overtreatment can cause other heart problems, like an irregular heart rate.

Living a healthy lifestyle, including eating well, staying active, and getting enough sleep, can help you feel your best. It’s also important to monitor your health conditions and keep up with medical appointments. For diabetes, that means watching your blood glucose levels. With Hashimoto’s, your thyroid levels should be monitored.

Both conditions require ongoing lifetime management. Just like a type 1 diabetes diagnosis, a Hashimoto's diagnosis comes with a learning curve. Treatment may take some trial and error. Once you get into a good rhythm, don’t fall off the radar with your health care provider. Stay on track with your recommended screenings so your doctor can adjust your medications or treatment plan if any changes happen over time.

Talk With Others Who Understand

On myT1Dteam, the social network for people living with type 1 diabetes and their caregivers, more than 3,500 members come together to ask questions, give advice, and share stories about their day-to-day lives.

Is thyroid autoimmunity a problem for you? How do you manage thyroid dysfunction along with type 1 diabetes? Share your experience below, or start a conversation by posting on your Activities page.