What are the recommendations for anaesthetic management of a patient with Diabetes Mellitus (DM) Type 2 during the perioperative period?

Anaesthetic Management of Type 2 Diabetes Mellitus

Maintain intraoperative blood glucose between 0.90-1.80 g/L (5-10 mmol/L) using continuous insulin infusion when needed, prioritize regional anaesthesia when feasible, and avoid perioperative hyperglycemia above 1.80 g/L (10 mmol/L) as it significantly increases infection risk and mortality. 1

Preoperative Assessment and Optimization

Glycemic Control Evaluation

• Measure HbA1c and recent capillary blood glucose levels to assess baseline control and adjust treatments before surgery 1
• If HbA1c indicates poor control, consider therapeutic intensification before elective procedures, validated by an expert prescriber 1
• Screen for recent hypoglycemic episodes (blood glucose <0.7 g/L or <3.9 mmol/L), particularly in the last week, as these predict perioperative risk 1
• Any unexplained malaise in diabetic patients must be treated as hypoglycemia until proven otherwise, even with normal glucose readings 2

Critical Diabetes-Specific Complications

• Assess for gastroparesis through questioning about abdominal pain, bloating, and vomiting, as this creates aspiration risk requiring rapid sequence induction 1
• Evaluate for silent myocardial ischemia, present in 30-50% of T2D patients, through ECG and consider stress testing if major surgery with Lee score ≥2 1
• Measure glomerular filtration rate preoperatively as diabetic nephropathy increases acute renal failure risk 1
• Screen for cardiac autonomic neuropathy through orthostatic blood pressure changes and heart rate variability, as this increases sudden death risk 1

Medication Management

• Hold all non-insulin oral antidiabetic drugs on the morning of surgery 1
• Stop metformin from the evening before surgery (not just morning of) 1
• Administer usual insulin dose the evening before surgery 1
• Maintain insulin pumps until patient arrives in surgical unit, then immediately transition to continuous IV insulin infusion to prevent ketoacidosis 1

Intraoperative Management

Blood Glucose Targets and Monitoring

• Target blood glucose 0.90-1.80 g/L (5-10 mmol/L) intraoperatively to balance infection risk against hypoglycemia 1
• Perioperative hyperglycemia >1.80 g/L (10 mmol/L) increases morbidity and mortality, particularly from infection 1
• Hyperglycemia >2.5 g/L (13.5 mmol/L) carries 10-fold higher complication risk 1
• Monitor capillary blood glucose hourly during surgery, especially for lengthy procedures 2

Insulin Administration

• Use continuous IV insulin infusion via electronic syringe for T2D patients requiring insulin or experiencing stress hyperglycemia 1
• Do not rely on continuous glucose monitors (CGM) during surgery due to discrepancies with capillary blood glucose from altered hemodynamics and subcutaneous perfusion 1
• Administer corrective insulin if blood glucose exceeds 3.0 g/L (16.5 mmol/L) during the procedure 2

Anaesthetic Technique Optimization

• Prioritize regional anaesthesia when possible for superior postoperative pain control and reduced insulin resistance 1
• Either volatile-based or total intravenous anaesthesia is acceptable with no difference in cardiovascular outcomes 2
• Use multimodal analgesia to facilitate rapid recovery of bowel function and reduce insulin resistance 1

Adjunctive Measures

• Administer 4 mg dexamethasone (not 8 mg) combined with another antiemetic for PONV prophylaxis 1
• Prevent hypothermia aggressively as this worsens insulin resistance 1
• Minimize blood loss and employ minimally invasive techniques when feasible to reduce stress response 1

Postoperative Management

Immediate Recovery Period

• Continue hourly capillary blood glucose monitoring until patient is fully conscious and capable of self-management 1
• Maintain glucose infusion (G 10% at 40 mL/h) for insulin-dependent patients to prevent recurrent hypoglycemia 2
• For insulin pump users, use built-in bolus calculator to determine correction doses once alert 1

Transition to Normal Management

• Resume insulin pump basal infusion once patient can manage their device and is eating 1
• Start bolus insulin dosing with first postoperative carbohydrate ingestion 1
• Continue increased frequency monitoring for 1-2 days postoperatively to re-establish baseline status 1

Critical Pitfalls to Avoid

• Never proceed with elective surgery if blood glucose >250 mg/dL (13.9 mmol/L) or HbA1c >8.5-9% as this dramatically increases complication risk 3
• Do not aim for strict normoglycemia as this increases hypoglycemia frequency without improving outcomes 1
• Avoid stopping insulin pumps without immediate IV insulin replacement in T1D patients, as ketoacidosis develops within hours 1
• Do not use CGM readings for intraoperative glucose management due to lag time and perfusion-dependent inaccuracy 1
• Recognize that 40% of T1D and 10% of insulin-treated T2D patients have hypoglycemia unawareness, requiring more vigilant monitoring 2