Diabetes & Surgery

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

A simple guide to managing your diabetes before, during, and after a procedure

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Step 1 — Before Your Procedure

Ask for a morning list spot if possible (less fasting time)
Bring your insulin, injecting equipment, and hypo treatment (lollies, dextrose tablets) to hospital
Check your blood glucose levels more often in the days before surgery
Do not drive to hospital while fasting

You may need to be admitted the day before if you:

Have Type 1 diabetes
Have Type 2 diabetes managed with insulin
Have sub-optimally controlled diabetes
Are scheduled for major surgery with long fasting periods

Step 2 — Do You Take an SGLT2i Medication?

Are you taking Forxiga, Qtern, Xigduo, Jardiance, Jardiamet, or Glyxambi?

YES — I take one of these

Stop it 3 days before your surgery (day of surgery + 2 days before)
Surgery may be postponed if not stopped in time and ketone levels are raised
Restart only when eating and drinking normally (usually 3–5 days after surgery)

NO

Move on to Step 3 below.

SGLT2i — Ketone Alert Levels

If you have not stopped your SGLT2i medication before surgery, when you arrive in hospital the staff will check your ketone levels:

Ketones	Base Excess	Action
<1 mmol/L	> −5	No ketosis or metabolic acidosis. Consider proceeding with hourly ketone monitoring. Insulin/dextrose infusion may reduce risks.
>1 mmol/L	> −5	Ketosis without acidosis. Seek endocrinology advice. Consider proceeding with insulin/dextrose infusion. (HbA1c <9%/<75 mmol/mol)
>1 mmol/L	< −5	Ketosis WITH metabolic acidosis. Strongly consider postponing non-urgent surgery. Escalate to endocrinology and critical care.

Finger-prick ketone >0.6 mmol/L perioperatively or >1.5 mmol/L at any time — perform VBG or ABG to check pH.

Step 3 — Do You Take a GLP-1 Medication?

Are you taking Ozempic, Wegovy, Rybelsus (semaglutide), Mounjaro (tirzepatide), Trulicity, or Saxenda?

Option A — You've been told to stop it (that's OK)

Weekly injections (Ozempic, Wegovy, Mounjaro, Trulicity) — stop 1 week before surgery
Daily injections/tablets (Saxenda, Rybelsus) — stop on the day before surgery
Follow standard fasting instructions
Restart when eating and drinking normally after surgery

Option B — It's too late to stop it (ANZCA 2025)

Day before surgery: Follow a clear fluid diet for 24 hours (from waking the day before)
Day of surgery: Standard 6-hour fast, then nothing for 2 hours before — no SipTilSend
The absence of nausea or bloating does not mean your stomach is empty
If the 24-hour clear fluid diet was not completed, tell your anaesthetist — a gastric ultrasound may be needed

Why do these medications matter? GLP-1 medications slow stomach emptying, increasing the risk of aspiration (stomach contents entering your lungs) during anaesthesia. Your anaesthetist may use erythromycin to help your stomach empty faster — standard anti-nausea medications do not work for this.

Important

If you are continuing your GLP-1 medication and did not follow the 24-hour clear fluid diet, you may be treated as having a full stomach — your procedure may need to be postponed or managed with a rapid sequence induction.

Reference: 2025 ADS/ANZCA/GESA/NACOS Clinical Practice Recommendations

Step 4 — Tablets or Insulin?

TABLETS ONLY (not SGLT2i)

Fasting overnight: Skip your morning tablet. Restart with your evening meal after surgery.

On Metformin + major surgery: Stop Metformin on the day of surgery. Your doctor will check kidney function before restarting.

ON INSULIN

Your instructions depend on the type of insulin and time of surgery. See Step 5 below.

Step 5 — Insulin Instructions

Morning Surgery

Evening before: Take usual short-acting insulin with dinner. Reduce night-time / long-acting insulin by 50%.

Morning of surgery (fasting): No short-acting insulin. Type 1 patients — get IV access on admission.

After surgery: Check BGL in recovery. If eating by 10am, delay morning insulin and have a late breakfast. Resume normal insulin with evening meal.

Afternoon Surgery

Day before: Take your regular insulin doses as normal.

Morning of surgery: Early breakfast with a reduced dose of insulin (confirmed by your anaesthetist or endocrinologist).

After surgery: Resume insulin when eating and drinking normally. Overnight admission may be needed if blood sugars are unstable.

Dose Adjustments by Insulin Type

Rapid / Short-Acting

Novorapid, Humalog, Apidra, Actrapid, Humulin R

Only take with meals. Skip if fasting.

Long-Acting

Lantus, Levemir, Toujeo

Normal dose morning before
Half dose evening before
Half dose morning of
Normal dose evening after

Intermediate-Acting

Protophane, Humalin NPH

Normal dose morning before
Half dose evening before
Half dose morning of
Normal dose evening after

Pre-Mixed

Humalin 30/70, NovoMix 30, Penmix 30/40/50

Normal dose morning before
Half dose evening before
One third dose morning of
Normal dose evening after

Insulin Pump

Any pump device

Continue at your usual basal rate.

Step 6 — On the Day & After Surgery

Your blood sugar will be checked before, during, and after your procedure
BGL checked in recovery (PACU) and again when you reach the ward
Your anaesthetist will advise nursing staff on restarting your insulin
If you need an insulin drip, you'll be looked after in the Intensive Care Unit

Check Your Blood Sugar Levels

Check BGL every 2 hours on the day of surgery
Below 5.0 mmol/L — have glucose-containing clear fluids
Above 10.0 mmol/L — drink water or clear diet drinks only
Type 1 patients: never skip insulin completely (risk of diabetic ketoacidosis)

When to Seek Urgent Help

Contact your doctor or hospital immediately if you develop abdominal pain, nausea, vomiting, unusual tiredness, or fast breathing before or after surgery — these may be signs of diabetic ketoacidosis (DKA).

Based on Wollongong Private Hospital Diabetes Management Guideline (V1, Feb 2020).
Simplified for patient reference — always follow your doctor's specific instructions.