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DiabeteshubComplicationsDiseases more common in diabetesDiabetes and thyroidThyroid underactivity in diabetes

Thyroid underactivity in diabetes

People with diabetes, regardless of its type, are two to three times as likely to have underactive thyroid.

The image shows the thyroid gland, which is located in the lower part of the neck and at the front, on both sides of the trachea.
The thyroid is an organ located around the trachea in the lower part of the neck and weighs about 20 grams.

The most common reason for underactive thyroid (hypothyroidism) in people with type 1 diabetes is an autoimmune infection of the thyroid. In this case, TPO (thyroid peroxidase) antibodies are present in the blood either permanently or at some stage.

In thyroid underactivity, a message of the low level of thyroid hormone is sent to the pituitary gland. The pituitary gland then increases the production of TSH hormone (thyroid-stimulating hormone), increasing its level in the blood. The increased TSH level stimulates the production of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). However, the thyroid hormone level will gradually decrease, and symptoms of an under will occur.

If underactive thyroid of a person with diabetes is not treated, it can contribute to the incidence rate of low blood sugars. In underactive thyroid, the amount of LDL cholesterol in blood increases.

  • Tiredness

  • Being cold easily

  • Weight gain

  • Constipation

  • Slower heart rate

  • Dry skin

  • Rough feeling hair

  • Bloatedness

  • Lack of initiative

  • Trouble remembering things

  • Sluggishness of thinking

The treatment for underactive thyroid is thyroxine hormone replacement therapy. Often, the initial dose is half a pill or smaller, and the dose is gradually increased. The normal thyroxine dose for an adult is 0,1–0,2 mg in the morning, approximately half an hour before breakfast and any other medications which can hinder the absorption of thyroxine. Especially iron and calcium products, gastric acid neutralisers and sucralfate must be taken no sooner than four hours after taking thyroxine.

During pregnancy, a normal thyroid hormone level in the mother is necessary for the development of foetus’s brain. Once the pregnancy has started, the need for thyroid hormone increases to 0.025–0.050 mg per day. That is why approximately 0.025 mg of thyroxine is added to the previous daily thyroxine dose immediately once the pregnancy test turns positive. The target TSH level is 2.5 mU/ l or below during the first trimester and 3.0 mU/ l or below after it.

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Updated 8.11.2023

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