If you or your child lives with type 1 diabetes, you may have heard it called an “autoimmune disease.” Unless you’re already familiar with this term, its meaning can be a bit unclear.

You might gather from the term that the immune system is involved in type 1 diabetes, which is true. Understanding what an autoimmune disease is and how the immune system is involved in type 1 diabetes can help you better understand your condition.

How the Immune System Works

The immune system fights outside invaders, including bacteria, viruses, and parasites. These are called pathogens.

Most pathogens try to multiply once they’re inside your body. As they do this, they damage, kill, or change your healthy cells. Your body doesn’t want this to happen, so it produces antibodies. These proteins travel throughout your bloodstream, searching for threats and eliminating them.

To do their job, antibodies must be able to recognize pathogens as foreign. When pathogens try to attach to your body’s immune cells and destroy them, the cells recognize proteins on the invaders’ surfaces as not being part of the body. These proteins are called antigens. When the body detects antigens, it produces inflammation. That process helps destroy pathogens.

Sometimes, the invading pathogen causes symptoms. Other times, symptoms like fever are actually a result of your own body’s immune response.

After your body eliminates a pathogen, it usually keeps information about it. This allows it to respond faster if you come into contact with that particular pathogen again.

What Having an Autoimmune Disease Does to Your Body

When someone is diagnosed with an autoimmune disease, it means that the body’s immune system is attacking itself instead of just pathogens. In these cases, the body creates autoantibodies, which go after its own tissues.

Because the immune system is always on the attack, the body experiences symptoms of inflammation, such as:

• Tiredness
• Nausea
• Rash
• Pain
• Headache
• Dizziness

The exact symptoms a person living with an autoimmune disease experiences will differ based on the part or parts of the body affected. The immune system’s attacks can occur nearly anywhere, leading to a wide variety of possible symptoms.

Researchers don’t know exactly why these changes occur in the immune system. It seems that the body stops being able to figure out what is a healthy part of you and what is a pathogen, but the reason for that loss of recognition hasn’t been discovered yet.

More than 100 types of autoimmune disorders have been identified. Some are more common or better known, but all these conditions occur because of these processes in the body.

Type 1 Diabetes and Autoimmunity

Type 1 diabetes is considered an autoimmune disease. The exact cause of type 1 diabetes isn’t known, but we can talk about what happens with the immune system.

In type 1 diabetes, the body makes autoantibodies that attack the insulin-producing parts of the pancreas — specifically, the beta cells. Insulin is the hormone that allows blood glucose (blood sugar) to enter cells and be changed into energy. These assaults by autoantibodies severely limit insulin production or stop it altogether. So far, researchers have linked four types of autoantibodies with type 1 diabetes.

About 70 percent of people diagnosed with type 1 diabetes, including children and adolescents, have three or four of these autoantibodies when they get diagnosed. Fewer than 10 percent have just one, and between 4 percent and 7 percent have zero. The two main types in type 1 diabetes are islet cell and glutamic acid decarboxylase (GAD) autoantibodies.

Islet Autoantibodies

For years, islet antibodies have been the key antibodies that doctors look for in a diagnosis of diabetes. Islet autoantibodies appear when beta cells get damaged. A person’s level of islet antibodies can help show how their type 1 diabetes is progressing and determine their prognosis (outlook) with the condition.

Glutamic Acid Decarboxylase Autoantibodies

Autoantibodies against glutamic acid decarboxylase enzymes are also important in type 1 diabetes. Anti-GAD antibodies have been shown to be positive in almost 80 percent of children with type 1 diabetes, according to the journal African Health Sciences.

Sometimes, people who haven’t been diagnosed with type 1 diabetes have these autoantibodies. GAD autoantibodies could be positive up to 10 years before the diagnosis, per a 2021 study in the journal Diabetologia. Endocrinologists (specialists in hormone-related conditions) sometimes use tests for antibodies for early detection in people who are likely to develop type 1 diabetes later.

Type 1 Diabetes and Other Autoimmune Diseases

Researchers also know that being diagnosed with type 1 diabetes puts you at a higher risk of developing other autoimmune diseases.

The most common autoimmune disease that health care providers see alongside type 1 diabetes is an autoimmune thyroid disease. A review of research published from 1977 to 2018 found that 17 percent to 30 percent of people diagnosed with type 1 diabetes also have an autoimmune thyroid condition. A number of genetic factors link these two conditions. Researchers need to do more work to figure out exactly which genes cause these conditions and how they work. The most common thyroid condition is autoimmune thyroiditis, which leads to hypothyroidism (low thyroid function). A more severe but rare condition, which leads to elevated thyroid function, is called Graves’ disease.

About 6 percent of people living with type 1 diabetes also have celiac disease. Sometimes, people with type 1 diabetes don’t recognize symptoms of celiac disease, such as stomach problems or weight loss, because they think type 1 diabetes is the cause of all their symptoms.

Other autoimmune diseases that overlap with type 1 diabetes include:

• Autoimmune gastritis — Chronic inflammation of the stomach lining
• Rheumatoid arthritis — A chronic inflammatory disorder affecting joints
• Lupus — A systemic (bodywide) disease that affects tissues and organs
• Addison’s disease — A disorder that inhibits the adrenal glands from producing enough of certain hormones
• Vitiligo — A condition causing loss of skin color
• Pernicious anemia — Characterized by an inability to properly absorb vitamin B12
• Alopecia — Hair loss due to the immune system attacking hair follicles

If you or your child has been diagnosed with type 1 diabetes, talk to your doctor about any additional screenings they recommend. Knowing what conditions you have may change your treatment plan and help your doctor make sure you have the most effective diabetes management that you can get.

Type 2 Diabetes and Autoimmunity

When doctors do blood tests and find autoantibodies in the bloodstream, they know the person should be diagnosed with type 1 diabetes and not type 2. In type 2 diabetes, the body is making insulin, but either it can’t make enough or the hormone doesn’t work the way it should.

Traditionally, type 2 diabetes hasn’t been considered an autoimmune condition. However, recent research is bringing that idea into question. Researchers have noticed immune system changes in some people who have type 2 diabetes. Diabetes care teams also note that type 2 diabetes involves chronic inflammation. These findings have led some researchers to wonder if type 2 diabetes is also an autoimmune disease or at least has an autoimmune component.

Talk With Others Who Understand

On myT1Dteam, find the social network for people with type 1 diabetes and their loved ones, more than 3,000 members come together to ask questions, give advice, and share their stories with others who understand life with type 1 diabetes.

Have you wondered if type 1 diabetes is an autoimmune disease? Are you living with any autoimmune diseases that overlap with type 1 diabetes? Share your experience in the comments below, or start a conversation by posting on your Activities page.