What are the recommendations for managing blood glucose levels in patients with diabetes undergoing anesthesia?

From the Guidelines

Managing blood glucose levels in diabetic patients undergoing anesthesia requires careful monitoring and adjustment of insulin therapy, with a target blood glucose range of 100-180 mg/dL (5.6-10.0 mmol/L) during the perioperative period, as recommended by the most recent guidelines 1. To achieve this target range, several strategies can be employed:

• A preoperative risk assessment should be performed for people with diabetes who are at high risk for ischemic heart disease and those with autonomic neuropathy or renal failure 1.
• Metformin should be held on the day of surgery, and SGLT2 inhibitors should be discontinued 3-4 days before surgery 1.
• Other oral glucose-lowering agents should be held the morning of surgery or procedure, and insulin dose reductions may be necessary, such as reducing NPH insulin to one-half of the dose or long-acting basal insulin analogs to 75-80% of the usual dose 1.
• Blood glucose should be monitored at least every 2-4 hours while the individual takes nothing by mouth, and short- or rapid-acting insulin should be administered as needed 1.
• Basal insulin plus premeal short- or rapid-acting insulin (basal-bolus) coverage has been associated with improved glycemic outcomes and lower rates of perioperative complications compared with reactive, correction-only short- or rapid-acting insulin coverage alone with no basal insulin dosing 1. It is essential to note that stricter perioperative glycemic goals are not advised, as they may not improve outcomes and are associated with increased hypoglycemia 1. Key considerations for managing blood glucose levels in diabetic patients undergoing anesthesia include:
• Monitoring blood glucose regularly and adjusting insulin therapy as needed
• Using basal-bolus insulin coverage for improved glycemic outcomes
• Avoiding stricter perioperative glycemic goals due to the risk of hypoglycemia
• Holding oral glucose-lowering agents and reducing insulin doses as necessary
• Providing education on the recognition, prevention, and management of diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS) for all individuals affected by or at high risk for these events 1.

From the FDA Drug Label

The intravenous administration of Humulin R U-100 was tested in 21 patients with type 1 diabetes The patients' usual doses of insulin were temporarily held, and blood glucose concentrations were maintained at a range of 200 – 260 mg/dL for one to three hours during a run-in phase of intravenous Humulin R U-100 followed by a 6-hour assessment phase. During the assessment phase patients received intravenous Humulin R at an initial dose of 0. 5 U/h, adjusted to maintain blood glucose concentrations near normoglycemia (100 to 160 mg/dL).

The recommendations for managing blood glucose levels in patients with diabetes undergoing anesthesia include maintaining blood glucose concentrations near normoglycemia (100 to 160 mg/dL) using intravenous insulin, such as Humulin R U-100, at an initial dose of 0.5 U/h, adjusted as needed.

• Key considerations include:
  • Temporarily holding the patient's usual insulin doses
  • Maintaining blood glucose concentrations within a target range
  • Adjusting the insulin dose to achieve near normoglycemia
  • Monitoring blood glucose levels closely during the assessment phase 2

From the Research

Diabetes Anaesthesia Considerations

• The management of blood glucose levels is crucial for patients with diabetes undergoing anesthesia, as uncontrolled high blood sugar can lead to severe complications 3.
• Elective surgery should be withheld if blood glucose levels exceed 250 mg/dl or HbA1c levels are higher than 8.5 - 9% to minimize the risk of severe complications 3.
• Blood glucose levels should be targeted to 140 - 180 mg/dl on intensive care units or during surgery to reduce negative outcomes 3.

Perioperative Blood Glucose Management

• Non-critically ill diabetics should be treated with rapid-acting insulin analogues subcutaneously in operating theatres, whereas critically ill patients should receive continuous intravenous insulin infusions using a standardized protocol 3.
• The preoperative assessment of patients with diabetes should include the evaluation of the patient's usual level of control and self-management skills and the occurrence of hypoglycemia 4.
• The perioperative administration of diabetes medications, insulin, and certain other drugs is a topic of dispute, and current recommendations for ambulatory surgery and anesthesia for diabetic patients should be followed 4.

Recommendations for Ambulatory Surgery

• The Society for Ambulatory Anesthesia has updated its consensus statement on perioperative blood glucose management in adult patients with diabetes mellitus undergoing ambulatory surgery, which includes recommendations for preoperative evaluation, management of preoperative oral hypoglycemic agents and home insulins, intraoperative testing and treatment modalities, and blood glucose management in the postanesthesia care unit and transition to home after surgery 5.
• High-quality evidence pertaining to perioperative blood glucose management in patients with diabetes undergoing ambulatory surgery remains sparse, and recommendations are based on recent guidelines and available literature 5.
• The benefits and risks of interventions and clinical practice information were considered to ensure that the recommendations maintain patient safety and are clinically valid and useful in the ambulatory setting 5.

Glucose Control and Medications

• Glucose fluctuations and hypoglycemia may pose greater risks to patients than elevated glucose itself, and new medications and insulin regimens make perioperative blood glucose control easier 6.
• The pharmacology of diabetes medications and the type of surgery and patient's degree of diabetic control should be considered when determining perioperative diabetes management 7.
• Perioperative control of blood glucose levels is associated with less morbidity and improved surgical outcomes in patients with and without diabetes mellitus, and preoperatively, clinicians need to thoughtfully adjust diabetic medications on the basis of patient comorbidities, the duration of the fasting period, and the duration of surgery 7.