Thyroid Disease and Diabetes

Lowering the risk of thyroid disease in those with diabetes:

Thyroid disease is common, especially among those with diabetes. About 7% of the general population has some type of thyroid disease. The incidence goes up to about 12% in those with type 2 diabetes, and as much as a one-in-three chance of developing thyroid disease if you have type 1 diabetes.

Your thyroid is a small, butterfly-shaped gland that is located in the lower part of your neck. It wraps around your windpipe, more formally known as your trachea. Though your thyroid is small it plays a very important role in regulating certain biological processes, such as growth, development, and metabolism.

It is most often thought of as the regulator of your metabolism. Your thyroid produces hormones that tell the body to either burn energy quickly, which causes a faster metabolism, or withhold these hormones to slow down the activity of the body.

Thyroid disease, like diabetes, produces an imbalance in hormones. In diabetes, the hormone that causes the imbalance is insulin. In thyroid disease, the hormones that are usually out of balance are called T4 and T3.

Two of the most common thyroid-related conditions are hyperthyroidism and hypothyroidism. In hyperthyroidism, your thyroid is overactive and produces too much of the thyroid hormone.

In hypothyroidism, your thyroid is underactive and does not produce enough of the thyroid hormone. In hypothyroidism, the pituitary gland overproduces thyroid hormone to compensate for a thyroid that isn’t producing enough.

Because there is an abundance of thyroid hormone with hyperthyroidism, the symptoms typically reflect a speeding up of the metabolic process and include:

• sweating
• weight loss
• diarrhea
• distraction
• rapid heart rate
• menstrual changes in women

Conversely, hypothyroidism is a deficiency of thyroid hormones and the symptoms indicate a slowing of the metabolic system. These symptoms include:

• fatigue
• lethargy
• depression
• constipation
• weight gain
• low blood pressure
• slow pulse
• intolerance to cold

A simple blood test measures the level of thyroid hormone and can detect whether the thyroid is producing too much or too little.

The presence of one autoimmune disease, such as diabetes, increases your risk of developing another autoimmune disease, such as thyroid disease. Because there is a significant risk of thyroid problems for those with type 1 diabetes, the American Diabetes Association (ADA) recommends that everyone with type 1 is tested for hypothyroidism soon after their diagnosis. If the thyroid is functioning properly at diagnosis, the ADA recommends follow-up tests be performed at least once every two years.

Testing is also recommended for women with type 1 who are pregnant. Hormonal changes are very common during pregnancy, and routine testing for thyroid problems in women with type 1 will help keep mother and child from experiencing adverse effects associated with thyroid disease.

Thyroid disease can make it more difficult to manage blood glucose. For example, with hyperthyroidism, the metabolism is increased due to an abundance of thyroid hormone. This can cause medications, such as insulin, to be processed and eliminated from the body more quickly than normal. Some people with type 1 who are also diagnosed with hyperthyroidism, may need to take higher doses of insulin for a time until their thyroid hormones are stabilized.

The opposite is true of hypothyroidism, where the metabolism is slowed. Insulin may linger longer in the body causing a greater risk of low blood sugar (hypoglycemia).

It’s important that you not adjust your prescribed insulin doses to compensate for thyroid disease until after you’ve discussed your condition with your doctor.

Hypothyroidism can be effectively treated with a synthetic version of thyroid hormone that is taken orally. Hyperthyroidism can also be treated with medication or radioactive iodine; in some cases, surgery may be necessary to remove some or all of the thyroid gland.

American Diabetes Association. "Detecting Thyroid Disease.”