Whether you need to take metformin to supplement vitamin B12 depends on whether the patient is suffering from vitamin B12 deficiency, if there is vitamin B12 deficiency, you can supplement vitamin B12. Metformin belongs to the class of biguanide glucose-lowering drugs, which can be used for patients with type 2 diabetes mellitus who are ineffective in the treatment of diet control and physical exercise, and can also be used for those who are obese with hyperinsulinemia. Taking large doses of metformin for a long time may cause damage to the mucosa of the gastrointestinal tract and affect the absorption of vitamin B12. Vitamin B12 deficiency may cause nausea, indigestion, loss of appetite, weight loss, menstrual irregularities, headache, memory loss, inflammation of the digestive tract, etc. It is recommended to take supplementation under the guidance of a doctor, and there is no vitamin B12 deficiency, and it is usually not supplemented. Whether you need to take metformin to supplement vitamin B12 should be under the guidance of a doctor according to the specific condition, not unauthorized use of medication, so as not to delay the condition.