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Metformin May Lower Levels of Thyroid Hormone

Thyroid disease is one of the most common endocrine disorders among the population. Within that spectrum, hypothyroidism – or a low production of thyroid hormones – is even more common among those who are diagnosed with diabetes.

A new, 25 year study published in the Canadian Medical Association Journal (or CMAJ) revealed that persons who have hypothyroidism and were also taking Metformin to control their glucose levels had a 55% greater risk of a lowered TSH (or thyroid stimulating hormone) level than those who instead, took sulfonylureas. The study looked at over 74,000 patients and tracked their changes in thyroid stimulating hormone levels. The thyroid stimulating hormone is a hormone that the pituitary gland produces in order to indicate to the thyroid – a butterfly shaped organ present in the neck region – that it needs to produce more hormones. The hormones that the thyroid produces, mainly T4 and T3, help regulate metabolism, and vitamin absorption, among other functions.

Hypothyroidism is more common among the aging population, especially with women. It is important that persons with diabetes get tested periodically for thyroid dysfunction. Some of the more significant signs of hypothyroidism are:

  • Exhaustion/loss of energy;
  • Inability to focus on daily tasks;
  • Mood swings and irritability or depression;
  • Dry skin;
  • Constipation;
  • Hair loss/fine hair;
  • Impaired menstruation;
  • Neck discomfort/enlargement of the neck area;
  • Carpal tunnel or joint pain;
  • Facial swelling;
  • Hoarse voice;
  • High cholesterol/metabolic syndrome issues.

Metformin is still a wonderful medication choice for managing type 2 diabetes, and insulin resistance in many patients. It also has shown promise in helping prevent other conditions such as breast cancer, and even in reducing the risk of miscarriage for women with Polycystic Ovarian Syndrome.

If you are currently taking Metformin, and a thyroid hormone replacement therapy, it is important to have regularly scheduled visits with your endocrinologist in order to keep track of your T4, T3, and TSH levels. There are many medications that may impact how thyroid hormones are absorbed – and it may take juggling around one’s medication schedule, as well as taking thyroid hormone pills on an empty stomach for the most success.

This should not discourage anyone from considering Metformin as a worthy alternative for managing blood glucose levels.

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.