Breastfeeding women are not allowed to take metformin, so as to avoid the drug ingredients entering the baby’s body through breast milk and causing abnormalities in the baby. Metformin is a commonly used clinical hypoglycemic drug for diabetic patients who are not satisfied with the effect of simple dietary control and have poor efficacy in the application of sulfonylureas. The description of the drug clearly indicates that it is prohibited for pregnant women and nursing mothers, because metformin can be metabolized through breast milk, and the drug components may enter the baby’s body through breast milk, leading to hypoglycemia or inducing other accidental conditions in the baby. Some patients may experience adverse reactions such as nausea and vomiting, diarrhea, and abnormal taste after applying Metformin. Metformin is contraindicated in special groups such as allergy to drug components, severe infection, alcoholism, renal dysfunction, acute or chronic metabolic acidosis. If a breastfeeding woman must use metformin, she should stop breastfeeding for a period of time. It is recommended that breastfeeding women with a high glycemic index follow the doctor’s instructions to use medication, and not to use medication indiscriminately on their own. Pay attention to the rationality of daily diet and limit the intake of sugary foods.