Anaesthetic Considerations in Diabetic Patients | Medical Lecture
Anaesthetic Considerations in Diabetic Patients
A Comprehensive Lecture for Medical Students and Residents
Dr. Ali Al-Saedi, MD
Family Medicine Physician & Community Medicine Educator
🎯 Learning Objectives
- Understand the pathophysiological changes in diabetes affecting anaesthetic management
- Conduct comprehensive preoperative assessment of diabetic patients
- Implement evidence-based perioperative glycaemic control strategies
- Recognize and manage diabetes-specific complications during anaesthesia
- Develop practical protocols for medication management in the perioperative period
1. Introduction: Why Diabetes Matters in Anaesthesia
Patients with diabetes mellitus represent approximately 15-20% of surgical populations globally [[48]]. They face significantly higher perioperative risks including:
- 2-3× increased risk of cardiovascular complications
- Higher incidence of surgical site infections (SSI) with glucose >180 mg/dL [[32]]
- Increased risk of acute kidney injury (AKI)
- Prolonged hospital stays and higher healthcare costs
The primary goal of perioperative management is not achieving normoglycaemia, but avoiding extremes—preventing both dangerous hypoglycaemia (<70 and="" dl="" hyperglycaemia="" mg="" significant="">180 mg/dL) that impairs immunity and wound healing.
2. Preoperative Assessment: Beyond Glucose Numbers
2.1 Diabetes-Specific History
- Type & Duration: Longer duration (>10 years) correlates with higher complication risk
- Glycaemic Control: HbA1c should be checked ≥1 week preoperatively. Target: <8.5% for elective surgery; consider postponing if >9% in high-risk procedures [[7]]
- Hypoglycaemia Awareness: Frequency of episodes, especially nocturnal
- Medication Regimen: Document all agents including newer classes (SGLT2 inhibitors, GLP-1 agonists)
2.2 Screening for Diabetic Complications
Cardiovascular System:
- Silent myocardial ischaemia occurs in 20-40% of diabetics due to autonomic neuropathy [[22]]
- Assess for angina equivalents: dyspnoea, fatigue, arrhythmias
- Consider echocardiography if symptoms suggest cardiomyopathy
Autonomic Neuropathy (Critical Assessment):
- Screen with simple questions: orthostatic dizziness, gastroparesis symptoms, resting tachycardia, erectile dysfunction
- Patients with autonomic neuropathy face:
- Unstable haemodynamics during induction/maintenance
- Blunted heart rate response to hypovolaemia/hypoxia
- Increased risk of intraoperative hypothermia [[21]]
- Potentially life-threatening hypotension with regional anaesthesia [[29]]
Renal Function:
- Check eGFR and urine albumin:creatinine ratio
- Renal impairment increases risk of contrast nephropathy, drug accumulation, and electrolyte disturbances
- Preoperative renal failure is the strongest predictor of cardiac complications in diabetics [[44]]
Airway & GI Considerations:
- Gastroparesis → delayed gastric emptying → increased aspiration risk
- Consider rapid sequence induction (RSI) for patients with symptomatic gastroparesis [[3]]
- Stiff joint syndrome may complicate airway management
3. Perioperative Glycaemic Management
3.1 Target Blood Glucose Ranges
Current consensus guidelines recommend maintaining blood glucose between 100–180 mg/dL (5.6–10.0 mmol/L) throughout the perioperative period [[38]].
Acceptable range: 80–200 mg/dL for most procedures; tighter control (110–150 mg/dL) may benefit cardiac surgery patients [[30]].
Acceptable range: 80–200 mg/dL for most procedures; tighter control (110–150 mg/dL) may benefit cardiac surgery patients [[30]].
3.2 Preoperative Medication Management
| Medication Class | Day of Surgery Recommendation | Rationale |
|---|---|---|
| Metformin | Withhold morning of surgery; restart when oral intake resumed & renal function stable | Risk of lactic acidosis with hypoperfusion/contrast exposure |
| SGLT2 Inhibitors (empagliflozin, dapagliflozin) |
Withhold ≥24h (type 2) to 48h (type 1) preoperatively | Risk of euglycaemic diabetic ketoacidosis (euDKA) during fasting/stress [[3]] |
| GLP-1 Agonists (semaglutide, liraglutide) |
Weekly agents: withhold 1 week pre-op Daily agents: withhold 24–48h pre-op |
Delayed gastric emptying → increased aspiration risk |
| Sulfonylureas | Withhold morning dose | Risk of prolonged hypoglycaemia under anaesthesia |
| Insulin (Long-acting) | Continue at 70–80% of usual dose | Maintains basal coverage while reducing hypoglycaemia risk |
| Insulin (Short-acting) | Withhold; replace with IV insulin protocol | Unpredictable absorption during fasting/stress |
3.3 Intraoperative Management
- Monitoring: Check capillary blood glucose hourly (more frequently if unstable)
- Insulin Protocol: Use variable rate insulin infusion (sliding scale) rather than fixed-rate for unstable patients
- Fluid Management:
- Avoid dextrose-containing fluids unless treating hypoglycaemia
- Use balanced crystalloids (e.g., Plasmalyte) over normal saline to avoid hyperchloraemic acidosis
- Monitor electrolytes—especially potassium (shifts with insulin administration)
- Corticosteroids: Low-dose dexamethasone (4 mg) is acceptable for PONV prophylaxis in most diabetics [[10]]
⚠️ Critical Alert: Hypoglycaemia under anaesthesia is particularly dangerous because autonomic warning signs (sweating, tremor, tachycardia) may be absent in patients with autonomic neuropathy. Maintain vigilance with frequent glucose monitoring.
3.4 Postoperative Care
- Continue hourly glucose monitoring until eating regularly
- Transition to subcutaneous insulin when patient tolerates oral intake:
- Give first subcutaneous dose 1–2 hours BEFORE stopping IV insulin
- Overlap prevents rebound hyperglycaemia
- Resume oral agents only when renal function confirmed stable and oral intake adequate
- Early mobilisation reduces insulin resistance and infection risk
4. Special Considerations by Anaesthetic Technique
4.1 General Anaesthesia
- Induction agents may cause more profound hypotension in patients with autonomic neuropathy
- Avoid prolonged fasting—schedule diabetic patients early in the operating list [[17]]
- Consider depth of anaesthesia monitoring (BIS) to avoid excessive dosing
4.2 Regional Anaesthesia
- Benefits: Reduced surgical stress response, better pain control, earlier mobilisation
- Cautions:
- Autonomic neuropathy → exaggerated hypotension with sympathetic blockade
- Peripheral neuropathy may mask compartment syndrome or pressure injuries
- Coagulopathy risk if renal impairment present
- Monitor blood pressure closely; have vasopressors readily available
5. Summary: The 5 Pillars of Safe Anaesthesia in Diabetics
- Comprehensive Preoperative Assessment: Screen for autonomic neuropathy, cardiovascular disease, and renal impairment—not just HbA1c
- Strategic Medication Management: Know when to withhold newer agents (SGLT2i, GLP-1 RA) to prevent euDKA and aspiration
- Targeted Glycaemic Control: Maintain 100–180 mg/dL; avoid both hypoglycaemia and significant hyperglycaemia
- Vigilant Intraoperative Monitoring: Hourly glucose checks, careful fluid/electrolyte management, anticipate haemodynamic lability
- Structured Transitions: Safe handover from IV to subcutaneous insulin; delayed restart of oral agents until renal function confirmed
Frequently Asked Questions
Q1: Should we postpone surgery for a patient with HbA1c of 9.2%?
A: Not automatically. For urgent/emergent procedures, proceed with intensive intraoperative glucose control. For elective intermediate/high-risk surgery, consider 4–6 weeks optimisation if HbA1c >9%, especially with evidence of end-organ damage. Low-risk procedures (cataract, minor skin surgery) may proceed with careful monitoring [[7]].
Q2: My diabetic patient on empagliflozin needs emergency surgery tonight. What should I do?
A: Check venous blood gas immediately for ketones—even with normal glucose. If ketones present, treat as euDKA with IV fluids + insulin + potassium replacement before proceeding. If no ketones, proceed with surgery but monitor glucose and ketones hourly intraoperatively [[3]].
Q3: Is tight glycaemic control (80–110 mg/dL) better than moderate control (140–180 mg/dL)?
A: No. Landmark trials (NICE-SUGAR) showed increased mortality with tight control due to hypoglycaemia risk. Current guidelines uniformly recommend 140–180 mg/dL as the safe target range for most surgical patients [[38]].
Q4: How do I recognise autonomic neuropathy quickly at preoperative assessment?
A: Ask three questions: (1) "Do you feel dizzy when standing quickly?" (orthostasis), (2) "Do you have persistent nausea/fullness after meals?" (gastroparesis), (3) "Is your heart rate always fast even at rest?" (resting tachycardia). Positive responses warrant haemodynamic caution [[22]].
Key References & Guidelines
- Polderman JAW, et al. Update on the perioperative management of diabetes. BJA Education. 2024. [[7]]
- Dogra P, et al. Diabetic Perioperative Management. StatPearls. 2024. [[6]]
- Society for Ambulatory Anaesthesia (SAMBA). Updated Consensus Statement on Perioperative Blood Glucose Management. 2023.
- Nicholson G, et al. Diabetes and adult surgical inpatients. BJA Education. 2011. [[41]]
- Oakley I, et al. Diabetic cardiac autonomic neuropathy and anesthetic management. Minerva Anestesiol. 2011. [[22]]
- Joint British Diabetes Societies (JBDS). Peri-operative management of adults with diabetes. 2023 update.
#DiabetesAndAnaesthesia
#PerioperativeMedicine
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#AutonomicNeuropathy
#PatientSafety
#MedicalEducation
#AnaesthesiaComplications
#SurgicalSafety
💡 Your Turn: Have you encountered challenging cases managing diabetic patients perioperatively? Share your experiences or questions in the comments below—let's learn together and improve patient outcomes through shared clinical wisdom. What aspect of diabetic perioperative care do you find most challenging in your practice?
© 2026 Dr. Ali Al-Saedi | For Educational Purposes Only | Always follow your institution's protocols and guidelines
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