Patients with Hashimoto’s thyroiditis alone cannot be treated with metformin; when Hashimoto’s thyroiditis is combined with diabetes mellitus, metformin can be taken to lower blood sugar as prescribed by the doctor. Metformin belongs to the biguanide class of hypoglycemic drugs, in the clinic is mainly used for diabetic patients of hypoglycemic treatment. Hashimoto’s thyroiditis is an autoimmune disease with thyroid tissue as the autoantigen, metformin is not used in the treatment of this disease. There is no cause-specific treatment for Hashimoto’s thyroiditis. For those with concomitant hypothyroidism, levothyroxine supplementation is usually required for treatment, and for those with goiter causing obvious compression symptoms or for whom medication is ineffective, surgery may be performed. It should be noted that metformin is contraindicated in patients with renal insufficiency, hepatic insufficiency, hypoxia, and hyperthermia. For patients with Hashimoto’s thyroiditis combined with diabetes mellitus can take metformin to lower blood sugar under the guidance of doctors. It is recommended that patients with Hashimoto’s thyroiditis actively cooperate with the doctor for treatment, and any medication should not be taken without authorization.