Because autonomic neuropathy affects the constriction of thermoregulatory blood vessels, it is more difficult for diabetic patients to maintain their own body temperature in cold environments than normal people, and therefore it is more difficult for diabetic patients to maintain a relatively constant body temperature regardless of the temperature of the environment than normal people. So are diabetic patients under general anesthesia more susceptible to intraoperative hypothermia? How does heart rate variability change in diabetic patients under general anesthesia? If diabetic patients are more susceptible to intraoperative hypothermia under general anesthesia, is this related to their cardiac autonomic dysfunction?

According to the latest version of data released by the International Diabetes Federation (IDF) in 2021, it can be seen that the number of people with diabetes globally or in China is high and the percentage is increasing.In 2021, there are 537 million people with diabetes globally, and there are about 141 million in China, which is an increase of about 21.55% compared with 2019 . Perioperative hypothermia is a clinical phenomenon in which a patient's core body temperature is below 36°C for non-medical purposes during the perioperative period, with an incidence of about 7-90%, which can lead to a variety of adverse outcomes.In hot environments, sweating and vasodilation are severely compromised in diabetic patients due to autonomic neuropathy, which prevents the body from transferring heat from the inside of the body to the skin through vasodilation, increased blood flow, and sweating. Similarly, because autonomic neuropathy affects the constriction of thermoregulatory blood vessels, it is more difficult for diabetic patients to maintain their own body temperature in cold environments than normal people, and therefore it is more difficult for diabetic patients to maintain a relatively constant body temperature regardless of the temperature of the environment than normal people. On the other hand, general anesthesia and external environmental factors in the operating room increase the incidence of intraoperative hypothermia, and theoretically, diabetic patients are more prone to dramatic fluctuations in their own body temperature during surgery, making it difficult for them to adapt to changes in the external environment. Due to the complex pathophysiological mechanism of diabetes, which affects multiple systems throughout the body, there are currently more than 100 complications of diabetes, of which autonomic neuropathy has the most serious impact on diabetic patients. Cardiac autonomic neuropathy is one of the most common and serious complications of diabetic autonomic neuropathy, with a prevalence of 63% . And heart rate variability is one of the most common tests for diabetic cardiac autonomic dysfunction. So are diabetic patients under general anesthesia more susceptible to intraoperative hypothermia? How does heart rate variability change in diabetic patients under general anesthesia? If diabetic patients are more susceptible to intraoperative hypothermia under general anesthesia, is this related to their cardiac autonomic dysfunction? However, there are still no studies and little attention has been paid to it.

Inclusion Criteria:

• 18 years old ≤ age ≤ 80 years old, gender is not limited;
• BMI index of 18-35 kg/m2 (including 18 kg/m2 and 35 kg/m2 );
• Diagnosed with diabetes mellitus;
• ASA Ⅰ - Ⅱ;
• Elective laparoscopic abdominal surgery under general anesthesia;
• Operating time >2 hours and <6 hours;
• Voluntary participation and signing of an informed consent form;
• Ability to be followed up in a timely manner.

Exclusion Criteria:

• Abnormally elevated preoperative inflammatory indicators;
• Core body temperature ≥37.5 degrees Celsius;
• Patients with previous clear central nervous system disease, history of psychiatric disorders, or epilepsy;
• Patients with verbal communication or hearing or visual impairment, who were unable to communicate well and had poor compliance;
• Intraoperative use of vasodilator (uradil, sodium nitroprusside, nitroglycerin);
• Any high-risk subjects with complete atrioventricular block or complete atrioventricular conduction tissue without implanted pacemakers, multiple premature ventricular beats, single premature ventricular beats (heart rate <45 beats/min), heart failure in NYHA (New York Heart Association) class III or higher;
• Subjects with any other clinically significant 12-lead electrocardiogram (ECG) or echocardiogram abnormality at the time of screening, ejection fraction (EF) <40%, or any other significant abnormality in the opinion of the investigator;
• Subjects deemed by the investigator to be unfit for this clinical trial for any other reason (anesthesia assessment unfit for surgery or preanesthetic hypertension).

Withdrawal Criteria:

• Serious adverse events, abnormal laboratory tests, or other conditions that indicate no further benefit or increased risk to the subject's safety from continued participation in the study;
• Incomplete recording of critical data (temperature or heart rate variability);
• Unstable condition requiring further admission to the intensive care unit;
• Intraoperative use of dexmedetomidine; 5. Perioperative nerve block.

This study is expected to collect patients who are hospitalized in Zhujiang Hospital of Southern Medical University and are proposed to undergo surgery