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Fasting Guidelines

Fasting Guidelines

A guideline is an evidence-based recommendation to assist clinical decision-making — not a rule, but a framework that supports professional judgement.

What you can eat and drink before your procedure

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Standard Fasting Times

These apply to all patients having a general anaesthetic, sedation, or regional anaesthesia.

6 hours
No food

No solid food, milk, or drinks containing milk for 6 hours before your procedure

2 hours
Clear fluids OK

Water, black tea/coffee, apple juice, clear cordial — up to 2 hours before

Chewing gum & lollies: Treat as food — stop 6 hours before

What Are Clear Fluids?

YES — You can have:
  • Water
  • Black tea or black coffee (no milk)
  • Apple juice (no pulp)
  • Clear cordial
  • Sports drinks (e.g. Gatorade)
  • Clear broth
NO — Avoid these:
  • Milk or drinks with milk
  • Orange juice or juices with pulp
  • Smoothies
  • Protein shakes
  • Alcohol
  • Any food

Fasting with Diabetes

If you have diabetes, fasting requires extra care. See our Diabetes & Surgery guide for full details.

Key Points for Diabetic Patients:

  • Request a morning list spot to minimise fasting time
  • Tablets (not SGLT2i): Skip your morning dose. Restart with your evening meal.
  • SGLT2i (Forxiga, Jardiance, etc.): Stop 3 days before surgery
  • GLP-1 (Ozempic, Wegovy, Mounjaro): If told to stop — 1 week before (weekly) or day before (daily). If continuing — 24-hour clear fluid diet the day before (ANZCA 2025)
  • Metformin + major surgery: Stop on the day of surgery
  • Insulin: Adjust doses — see full insulin guide

BGL Monitoring While Fasting:

  • Check every 2 hours on the day of surgery
  • Below 5.0 mmol/L — have glucose-containing clear fluids (e.g. apple juice, clear cordial)
  • Above 10.0 mmol/L — drink water or clear diet drinks only
  • Type 1 patients: never skip insulin completely — risk of DKA

Bowel Preparation & Diabetes

If you need bowel preparation (e.g. for colonoscopy), special rules apply:

  • Oral medications: Omit while on clear fluids only. Restart after the test at lunchtime.
  • Insulin: Requirements will be less — you are taking in fewer carbohydrates from clear fluids
  • Check BGL 4–6 times daily during bowel prep
  • Type 1: Do not omit insulin completely — risk of DKA
  • Below 5.0 mmol/L — glucose-containing clear fluids
  • Above 10.0 mmol/L — water or clear diet drinks only
  • If on a large dose of insulin or unstable diabetes, arrange admission during bowel prep for close monitoring

Important Reminders

  • Do not drive to hospital while fasting
  • Take your regular non-diabetes medications with a sip of water (unless told otherwise)
  • If your surgery is delayed, tell staff you are diabetic so they can monitor your blood sugar
  • Bring your insulin, injecting equipment, and hypo treatment to hospital
Based on current Australian anaesthesia fasting guidelines and WPH Diabetes Management Guideline (V1, Feb 2020).
Always follow your anaesthetist's specific instructions.
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