Generally speaking, the standard of blood sugar control for patients before surgery depends on the size of the surgery and the daily patient’s blood sugar level.1. For small and medium-sized surgeries of the first and second level, the surgery is less traumatic, and the preoperative requirements for blood sugar are lower. Generally, patients with diabetes are required to have postprandial blood glucose control below 13mmol/L and fasting blood glucose control below 10mmol/L for surgical treatment. 2. For large surgeries such as grade 3 and 4, the operation time is longer and the surgery is more traumatic, and if the patient’s blood glucose is not well controlled after surgery, it will often cause incision infection and even long-term non-healing. It is recommended that patients should preferably control their blood sugar below 8 mmol/L fasting and 11 mmol/L after meal before surgery is performed more safely.