Can a patient with uncontrolled diabetes be cleared for anesthesia?

Management of Patients with Uncontrolled Diabetes for Anesthesia

Patients with uncontrolled diabetes should not be cleared for elective anesthesia until their blood glucose levels are adequately controlled, with a target HbA1c between 6-8% and blood glucose between 5-10 mmol/L (0.9-1.8 g/L). 1

Preoperative Assessment

• A recent HbA1c measurement is essential for determining perioperative risk and should be obtained for all diabetic patients before anesthesia 1
• An HbA1c value between 6-8% indicates good glycemic control and is reassuring about the quality of long-term treatment and patient compliance 1
• Values <6% may indicate risk of hypoglycemia, while values >8% suggest poor control and may warrant postponement of elective surgery 1, 2
• If blood glucose is >16.5 mmol/L (3 g/L) on the day of surgery, the procedure should be postponed and treatment with corrective insulin administered 1

Risk Assessment

• Uncontrolled diabetes significantly increases perioperative risks, including:

  • Higher rates of surgical site infections 3
  • Increased cardiovascular complications 3
  • Impaired wound healing 4
  • Greater risk of renal failure 3
  • Higher mortality rates 3

• For each unit increase in HbA1c, there is a significantly increased risk of myocardial infarction and deep sternal wound infection 3

• HbA1c >8.6% has been associated with a 4-fold increase in mortality following cardiac surgery 3

Decision Algorithm for Anesthesia Clearance

1. For emergency surgery:

   • Proceed with surgery regardless of glucose control
   • Implement intensive insulin protocol during perioperative period 1

2. For elective surgery:

   • If HbA1c is 6-8%:

     • Clear for anesthesia
     • Implement standard perioperative glucose monitoring 1

   • If HbA1c is <6%:

     • Assess for risk of hypoglycemia
     • Consider consultation with diabetologist 1
     • May proceed with close monitoring for hypoglycemia 1

   • If HbA1c is >8%:

     • For non-urgent procedures: postpone surgery and refer to diabetologist 1
     • For urgent procedures: proceed with intensive perioperative glucose management 1

   • If blood glucose on day of surgery is >16.5 mmol/L (3 g/L):

     • Postpone elective surgery 1
     • Administer corrective insulin bolus 1
     • Refer to diabetologist 1

Perioperative Management if Surgery Proceeds

• Target blood glucose range: 5-10 mmol/L (0.9-1.8 g/L) 1
• Monitor capillary blood glucose hourly during the procedure, especially for lengthy surgeries 1
• Administer insulin (ultra-rapid analogue) bolus if blood glucose >10 mmol/L (1.8 g/L) 1
• Resume oral feeding as soon as possible postoperatively 1
• Continue regular blood glucose monitoring postoperatively 1, 5

Common Pitfalls and Caveats

• Many patients may have undiagnosed diabetes or prediabetes; studies show up to 33.6% of elective surgery patients have previously undiagnosed dysglycemia 6
• Setting an HbA1c goal of ≤7.0% may be unrealistic for some patients; studies show only 59% of patients with HbA1c >7.0% were able to achieve this goal despite delaying surgery 2
• Intraoperative glucose monitoring is often neglected despite its importance; one study found only 33% of diabetic patients had intraoperative glucose checks 7
• Post-surgical hypoglycemia may be masked by sedation effects; always check glucose in any post-surgical patient with altered mental status 5

When to Consult a Diabetologist

Referral to a diabetologist is recommended in the following situations:

• Known diabetes with preoperative glycemic imbalance (HbA1c <5% or >8%) 1
• Diabetes discovered during pre-anesthesia evaluation 1
• Blood glucose >16.5 mmol/L (3 g/L) on day of surgery 1
• Difficulty resuming previous treatment regimen 1

By following these guidelines, the perioperative risks associated with uncontrolled diabetes can be significantly reduced, improving patient outcomes and reducing complications.