Metformin linked to risk of low thyroid-stimulating hormone

By M Tyler, Sep 22, 2014

Metformin, a drug commonly used to help lower blood glucose levels in diabetics, could pose a risk to thyroid health, according to a study published in the Canadian Medical Association Journal.

In patients who were already being treated for hypothyroidism (low thyroid), taking metformin was associated with a 55-percent increased risk of low thyroid stimulating hormone (TSH) levels when compared with individuals taking sulfonylurea, another antidiabetic drug.

The study included data on 73,000 patients over a 25-year period.

Thyroid and diabetes

Low TSH can sometimes indicate an overactive thyroid, but it's unclear exactly how metformin may influence TSH levels.

Symptoms of low TSH can include fatigue, nervousness, restlessness, muscle cramps and heat sensitivity.

Further complicating the matter is the evidence that insulin resistance can impact thyroid health, which could suggest that patients might have compromised thyroid health before they start taking metformin.

"Given the relatively high incidence of low TSH levels in patients taking metformin, it is imperative that future studies assess the clinical consequences of this effect," the study authors wrote.

Source: Science Daily

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