The reason why taking metformin doesn’t work may be due to insufficient dosage of the medication, insensitivity to the medication, or poor dietary control on a daily basis. Metformin is a glucose-lowering drug for type 2 diabetes mellitus that is ineffective in controlling blood glucose with diet or exercise therapy, and its common adverse reactions include nausea, vomiting, diarrhea, abdominal pain and loss of appetite. It is contraindicated in patients with diabetic ketoacidosis, severe infection, major surgery, trauma and heart failure. If taking Metformin doesn’t work, the dose of the drug may be insufficient or the patient may not be sensitive to the drug. In addition, if dietary control is not adhered to while taking the medication, it can also make the blood sugar not easy to lower. All of these factors can affect the efficacy of the drug, and it is recommended that patients seek timely medical attention and adjust the drug under the guidance of the doctor.