During minor and moderate surgeries (i.e., surgery time shorter than 1 h), it is not necessary to perform insulin therapy for patients with diabetes if the blood glucose levels are adequately controlled by the previously administered oral antidiabetic agents. (1B) Glucosidase inhibitors, DPP-IV inhibitors, GLP-1 analogues and PPAR-γ receptor agonists can be administered according to routine. During the fasting period, agents with high risk of causing hypoglycaemia, such as sulfonylurea drugs and non‐sulfonylurea insulin secretagogues should be stopped. (1B) Sodium–glucose cotransporter 2 (SGLT2) inhibitors should be avoided in case of surgical procedures. (2B)

Patients under intraoperative insulin therapy should continue to receive insulin therapy during the postoperative fasting period (24–48 h) until they start eating, following which oral anti‐diabetic agents can be resumed. (2C)

People with diabetes with normal renal function do not need to stop taking metformin before surgery. (2B) However, if the use of an intraoperative iodine contrast agent is necessary, metformin should not be taken 24 h before surgery. For patients with abnormal renal function, metformin should not be taken 48 h before surgery if using an iodine contrast agent and general anaesthesia, and it's administration should be suspended for 48–72 h postsurgery until renal function is normal. (2B) Metformin is not recommended when the glomerular filtration rate (eGFR) is 30–45 ml/(min•1.73 m2 ), and is prohibited when eGFR<30 ml/(min•1.73 m2). (1A)

All medical staff who intend to use insulin during the perioperative period should be specially trained, with provisions for regular updates and continuous education. If possible, there may be a written instruction manual for this. (2B)

People with diabetes on insulin therapy to control the blood glucose levels during the perioperative period are recommended to lose the blood glucose control target (random blood glucose control 6–10 mmol/L); (Evidence level:moderate; Recommendation grade:Strong). people with diabetes with good preoperative blood glucose control may continue to use insulin therapy, and the amount of insulin is adjusted according to the type of insulin and surgery time; if the random blood glucose level is more than 10.0 mmol/L on more than two occasions, insulin can be added to control blood glucose levels, and the original treatment plan can be adjusted. If the random blood glucose is still more than 10.0 mmol/L after using subcutaneous insulin therapy more than twice, short‐term intensive insulin therapy (multiple subcutaneous injections of insulin*/CSⅡ*/VRⅢ*) is recommended. (2C) .

Patients in the nonintensive units may consider the use of CSII to regulate blood glucose levels during the perioperative period. (2C) When using CSII, the base rate can be maintained before surgery. The preferred installation site for the subcutaneous infusion device is the abdomen, followed by the upper arm, lateral thigh, lower back, hip, and so forth, and the installation site needs should not be within 2–3 cm of the abdominal line, scars, induration owing to insulin injection, the belt position and umbilicus. Patients in the middle and late period of pregnancy need to be careful when injecting into their abdomen. (2B) Insulin used in insulin pumps are quick-acting human insulin analogues or short‐acting human insulin, with the former being more effective. Medium, long acting, premixed insulin should not be used for insulin pump therapy. (1B)

Hyperglycaemia is a risk factor for perioperative malnutrition and adverse clinical outcomes. Hence, regular monitoring of nutritional indicators and nutritional assessment should be performed for perioperative patients with hyperglycaemia.(1B) It is suggested that the physician should use the Nutritional Risk Screening Form 2002 (NRS2002) for preoperative assessment, especially for patients with other high nutritional risk factors (e.g., gastric bypass surgery) may be focused on screening. (2B)

Patients with high nutritional risk should use enteral nutrition preparations that are suitable for those with diabetes under the guidance of dietitians. (1B)

People with diabetes who receive continuous enteral nutrition or intravenous nutritional support may use variable rate intravenous insulin infusion (VRIII) or continuous subcutaneous insulin infusion (CSII) for blood glucose management. Patients receiving partial administration of enteral nutrition should be given a subcutaneous injection of short-acting/fast-acting insulin. (2C)

Peripheral blood glucose levels should immediately be examined after surgery. At the same time, the attending physicians and nurses should pay attention to the patient's postoperative rehabilitation, including the return to a normal diet and advanced preparations for discharge. (1B) Before discharge, relevant education should be provided to ensure the safe management of diabetes at discharge, including information on how blood glucose should be monitored, how oral antidiabetic agents and insulin are to be administered and when the patient should return for a follow-up visit. (1C)