Anaesthesia in diabetic patients undergoing surgery

Overview

Diabetes mellitus is associated with increased surgical morbidity, mortality, and prolonged hospital stay. Perioperative hyperglycaemia increases the risk of surgical site infections, medical complications, and death.

Preoperative considerations

Before surgery, the following should be considered:

• Ideally, elective surgery should be performed when:

  • Glycated haemoglobin (HbA1c) is <9%, or

  • Fasting blood glucose is ≤10 mmol/L, or

  • Random blood glucose is ≤13 mmol/L.

• Screen for diabetic complications, including:

  • Nephropathy

  • Cardiac disease

  • Retinopathy

  • Neuropathy

• Inform the surgical team of any diabetic complications identified.

Patients receiving oral hypoglycaemic agents

If the patient is receiving oral hypoglycaemic therapy, has good glycaemic control, and is scheduled for minor surgery:

• Omit the oral hypoglycaemic medication on the morning of surgery.

• Resume therapy once the patient is eating normally.

Patients receiving insulin

Management depends on the type of surgery and the expected fasting period.

Minor surgery (duration <3 hours)

Insulin

On the morning of surgery:

• Administer intermediate-acting insulin at ½ to ⅔ of the total daily dose.

If blood glucose is >20 mmol/L:

• Administer a small dose of short-acting insulin.

In the evening:

• Administer intermediate-acting insulin at ⅓ of the total daily dose.

Intravenous fluids

5% dextrose (IV)

• Administer an age-appropriate maintenance volume.

Blood glucose monitoring

• Monitor blood glucose every 1–2 hours.

• Target blood glucose: 10–14 mmol/L.

Major surgery (duration >3 hours)

Major surgery generally requires general anaesthesia and a prolonged fasting period.

Intravenous fluids

Administer an infusion containing:

• 5% glucose

• Potassium chloride 20 mmol/L

Use the appropriate maintenance fluid volume.

Insulin infusion

Insulin infusion

• 0.05 IU/kg/hour

Blood glucose monitoring

• Monitor blood glucose every 1–2 hours.

• Target blood glucose: 6–14 mmol/L.

If blood glucose falls below 5 mmol/L:

• Reduce the insulin infusion rate.

Continue insulin infusion throughout the intraoperative period.

Postoperative management

Continue intravenous therapy until oral intake has been re-established.

Administer:

• 5–10% dextrose (IV): 1 litre

• Potassium chloride: 20 mL

• Insulin: ⅔ of the patient's total daily dose

Infuse over 8 hours, and repeat as necessary until the patient resumes adequate oral feeding.