For diabetic patients in the doctor’s guidance under the standardization of taking metformin for six months can maintain blood sugar stability, but also may cause nausea, fatigue and other adverse reactions. Metformin belongs to the biguanide class of hypoglycemic drugs, can inhibit the synthesis of glucose in the liver, intestinal absorption of glucose, increase the uptake and utilization of glucose in peripheral tissues, so as to play a role in lowering the fasting and postprandial blood glucose, and can be used to treat patients with type 2 diabetes mellitus who can’t control their blood glucose well by diet or exercise alone. Taking metformin for six months may cause nausea, vomiting, diarrhea, loss of appetite, fatigue and other adverse reactions; and, long-term use of metformin may also reduce intestinal absorption of vitamin B12, resulting in anemia. It should be noted that people who are allergic to the drug, kidney disease, serious infection, trauma, diabetic ketoacidosis, etc. should not take metformin. Patients who need to take metformin treatment should be under the guidance of a doctor to standardize the use of medication, if the drug after the occurrence of uncomfortable symptoms recommended to go to the hospital.