People with type 1 diabetes are more likely to develop other autoimmune diseases, especially ones which can affect the thyroid gland.
Hashimoto's disease is an autoimmune disease that causes the body's immune system to turn on the thyroid gland, just as type 1 diabetes causes it to turn and attack the pancreas.
This attack on the thyroid gland causes hypothyroidism.
Graves' disease on the other hand causes the thyroid to become overactive, again because of a malfunction with the immune system.
It is thought about 30% of female type 1 diabetes patients will develop Graves' disease and suffer with their thyroid. In the non-diabetic population, women are about 10 times more likely to have the disease than men.
Graves' and Hashimoto's disease have no direct treatment, but hypothyroidism and hyperthyroidism do.
What does the thyroid do?
The thyroid is a gland in the neck, located just behind the muscle at the base of the neck and in front of the windpipe. It produces and releases several hormones that are related to body's metabolism.
The main hormones it releases are triiodothyronine and thyroxine, which help to regulate the growth and the rate of function of many of the body's systems.
Hyperthyroidism and Graves' disease
As a result of Grave's disease, the thyroid can become overactive and produce too many of the hormones.
It is unknown why it does, but Graves' disease causes some of the cells of the immune system to bond to receptors on the thyroid, and act like thyroid stimulating hormones, tricking it into over working and producing more hormones than it should.
In turn, this can cause the body's systems to speed up, resulting in a variety of symptoms and complications.
These can include:
- Weight loss
- Rapid heartbeat or heart palpitations
- Diarrhoea or excessive bowel movement
- Muscle weakness
- Feeling too hot
- Being able to tolerate cold temperatures
- Increased appetite
- Bulging eyeballs
- Irregular or absent menstruation
- Personality changes (anxiety, depression, agitation)
- Goitre (swollen thyroid and neck)
Hyperthyroidism is normally treated in one of two ways: with a dose of radioactive iodine to destroy cells in the thyroid, or with a thyroidectomy, surgery which removes some or all of the thyroid. Both cases reduce the ability of the thyroid to produce hormones, and so make the symptoms and complications go away.
In both cases however, follow up medication is likely to be needed.
Hypothyroidism and Hashimoto's disease
A lot of the symptoms for hypothyroidism can be seen as the opposite of those of hyperthyroidism. This is because hypothyroidism is an underactive thyroid, often caused by Hashimoto's disease.
This causes the immune system to attack the thyroid, reducing its ability to create hormones.
This slows down a lot of the metabolic processes in the body due to producing a low amount of thyroxine and triiodothyronine.
Symptoms of hypothyroidism include:
- Weight gain
- Sensitivity to the cold
- Dry skin
- Muscle aches
- Heart disease
- Personality changes (depression)
- Goitre (swollen thyroid and neck)
Hypothyroidism can be treated by taking daily medications that supply the body with the hormones that they thyroid cannot. Unfortunately, sufferers will likely have to be on medication for the rest of their life, but in most cases these drugs do not prevent the patient from leading a normal life and can prevent major complications, such as heart disease and pregnancy issues.
Diabetes and thyroidism
As thyroidism affects the body's metabolism, it can mean a big problem for diabetics. The hunger, muscle weakness and fatigue that can occur from either hypo- or hyperthyroidism can make sticking to a strict, healthy diet and getting in enough exercise difficult.
This is why it is important to be aware of the signs and symptoms and get checked for Graves' and Hashimoto's disease as soon as possible as it may affect blood glucose control.
Developing the disease
It is not known what causes the immune system to act oddly and affect the thyroid.
As with type 1 diabetes, some think it may be triggered by certain viruses and bacteria.
However, there are some factors that have been found to increase your chances of developing them.
It is known that having one autoimmune disease can leave you vulnerable to another autoimmune attack, so anyone with type 1 diabetes could be at greater risk of developing either Graves' disease or Hashimoto's disease, and vice versa.
Genetic susceptibility is also known to play a role, just like with type 1 diabetes, meaning Graves' and Hashimoto's diseases are more likely to develop if you have a close relative who has either the disease.
Women are also more susceptible to developing these diseases than men.