01Principles and purposeThe professional or clinical skill and the decisions it supports.
Surgery disrupts the usual relationship between food, activity and endocrine treatment. Fasting can lower glucose while stress hormones raise insulin requirements; nausea may prevent reliable oral treatment after the operation. Glucocorticoids can increase glucose further, yet withholding them from a dependent patient may cause haemodynamic collapse. The practical task is to preserve essential hormone replacement while adapting treatment to an unstable setting. A blanket instruction to omit diabetes medicines and steroids because the patient is fasting ignores their different roles.
In type 1 diabetes, basal insulin suppresses ketogenesis even when no meal is eaten. Meal-related insulin and basal provision therefore cannot be treated as interchangeable. An appropriate regimen may involve adjusted subcutaneous insulin or an intravenous strategy depending on procedure duration, missed meals, control and clinical stability. CPOC emphasises planning, limiting unnecessary fasting and involving diabetes expertise where needed. Glucose targets should avoid both hypoglycaemia and excessive hyperglycaemia; trying to achieve a narrowly normal value by repeated correction doses can produce dangerous oscillation.
Glucocorticoid dependence has two common routes: established adrenal or pituitary disease, and suppression after exogenous steroid exposure. Obtain the preparation, dose, route, duration and recent changes, including inhaled, injected or topical exposure where relevant. Surgical stress may require additional glucocorticoid beyond ordinary replacement. The cover needed for major surgery differs from that for a small procedure under local anaesthesia. Document who will prescribe the induction dose, continue postoperative replacement and reduce it during recovery; an induction-only order can leave a vulnerable patient uncovered later.
Key points
- Type 1 diabetes requires continuing insulin provision during fasting; stopping every insulin dose can cause ketoacidosis.
- Link insulin adjustments and monitoring to the expected missed meals, usual regimen and ability to self-manage.
- For perioperative patients with diabetes using SGLT2 inhibitors, measure capillary blood ketones daily until normal eating and drinking resume, even with normal glucose; assess immediately for ketones and acidosis if unwell.
- An insulin infusion requires the correct substrate, electrolyte monitoring and a planned transition back to usual therapy.
- Known adrenal insufficiency requires surgical stress cover; chronic glucocorticoid exposure may also suppress the adrenal response.
- Treat suspected adrenal crisis promptly with parenteral hydrocortisone and resuscitation rather than awaiting confirmatory tests.
02Situations and prioritiesThe context, relevant information and actions that matter most.
A fasting patient with type 1 diabetes needs an immediate review if no basal or intravenous insulin provision exists. A glucose value currently in range does not demonstrate that insulin deficiency is safe. Establish the last dose, glucose, ketones and clinical state and seek the appropriate diabetes or anaesthetic plan.
A patient exposed to an SGLT2 inhibitor may develop nausea, abdominal pain, tachypnoea or malaise with glucose that is not strikingly high. Check blood ketones and acid–base status promptly and assess for ketoacidosis. Do not attribute the symptoms solely to surgery or exclude the diagnosis from glucose alone.
A steroid emergency card, known adrenal insufficiency or significant glucocorticoid exposure should trigger a perioperative replacement assessment. Verify what was actually prescribed and administered. The absence of a steroid on the inpatient chart may represent a reconciliation error rather than a deliberate decision to stop it.
Hypotension, vomiting, weakness or hypoglycaemia in a person with adrenal insufficiency can signal crisis, particularly after missed medication or surgical stress. Escalate, resuscitate and administer emergency hydrocortisone promptly. Diagnostic sampling may be helpful if it causes no delay, but treatment must not wait for cortisol results.
03Assessment and interpretationHow to gather information, assess the situation and recognise uncertainty.
Consider the information, its meaning and its limitations before deciding what follows.
- 01
Map diabetes treatment to the operative timetable - Why
- Identify the diabetes type, usual regimen, technology and expected period without normal meals.
- Interpretation and limitations
- Record the last insulin and oral or injectable medicine doses. Ask about hypoglycaemia awareness, self-management skills and the availability of pumps or sensors. A patient’s usual successful routine is useful information, but anaesthesia may temporarily remove their ability to manage it.
- 02
Assess current control and metabolic stability - Why
- Distinguish longer-term optimisation from an acute emergency.
- Interpretation and limitations
- Assess current glucose and clinical stability alongside HbA1c, which does not identify an acute metabolic emergency. The 2026 Association/JBDS consensus targets 6–10 mmol/L with insulin, sulfonylureas or meglitinides, and 4–10 mmol/L with diet or other drugs. Define individual treatment thresholds; a value below 6 is not automatically hypoglycaemia requiring treatment in every regimen.
- 03
Plan ketone surveillance and assess metabolic risk - Why
- Identify metabolic complications and factors affecting treatment safety.
- Interpretation and limitations
- In perioperative diabetes with SGLT2 exposure, check capillary blood ketones daily until normal intake resumes even when glucose is normal. Check immediately if unwell and assess acid–base status with urgent senior review for abnormal ketones or suspected DKA. Electrolytes and kidney function influence treatment. A variable-rate glucose-management infusion is distinct from fixed-rate treatment of established DKA.
- 04
Establish the steroid replacement requirement - Why
- Determine whether the patient can mount an adequate stress response.
- Interpretation and limitations
- Review the underlying diagnosis and cumulative exposure rather than looking only at today’s dose. Where suppression is uncertain, obtain an endocrine or anaesthetic plan proportionate to surgical urgency. Do not abruptly stop chronic glucocorticoids while waiting for an elective assessment.
04Worked approachesCases with ordered reasoning, an action and a check of the outcome.
01Worked casePreserving basal insulin during a short fastAt 07:30, a stable 39-year-old with type 1 diabetes awaits a first-list elective operation. Their usual Lantus insulin glargine is 40 units subcutaneously at 08:00; the last dose was yesterday at 08:00. They use rapid insulin with meals. Glucose is 8.4 mmol/L, ketones 0.2 mmol/L and eGFR 90 mL/min/1.73 m². Only breakfast is expected to be missed, lunch intake is expected, and there is no acute illness. A fasting order has incorrectly omitted the morning basal dose.+
- 1Confirm the named insulin, usual dose, last actual administration and absence of another morning dose. Glucose is currently within the insulin-treated perioperative target, but fasting does not remove the basal requirement in type 1 diabetes.
- 2The anaesthetic and diabetes team agree adjusted subcutaneous treatment for this stable patient and single missed meal. Apply the CPOC/UKCPA once-daily morning glargine adjustment: 80% × 40 units = 32 units. Correct the prescription and administer 32 units subcutaneously at the usual 08:00 time after the appropriate checks.
- 3Omit the breakfast meal-related dose while that meal is omitted. Prescribe access to hypoglycaemia treatment and an agreed correction pathway; do not give an arbitrary rapid-insulin replacement for basal insulin. Check glucose on admission and at least hourly intraoperatively, recording results and actions.
- 4If delay means more than one meal will be missed, intake fails or metabolic instability develops, obtain urgent team review for the variable-rate intravenous insulin pathway with appropriate substrate and electrolytes. Preserve basal coverage; suspected DKA requires its separate emergency regimen.
- 5At recovery, verify actual insulin delivery, glucose and ability to eat before resuming the usual meal-related plan. Reassess the next basal dose against intake and recovery; if an infusion became necessary, document safe overlap and basal coverage before stopping it.
- 6Handover the exact 32-unit dose and time, latest glucose, next check and escalation contact. Reconcile the electronic chart with the patient and administering clinician so the corrected order cannot be duplicated.
02Steroid replacementMajor surgery in established adrenal insufficiencyAn adult with established primary adrenal insufficiency is having major surgery and is expected to be unable to absorb oral medicines afterwards.+
- 1Agree surgical stress cover with anaesthesia and endocrinology. The adult major-surgery approach uses hydrocortisone 100 mg intravenously at induction followed by 200 mg over twenty-four hours by continuous intravenous infusion while parenteral cover is required.
- 2Continue appropriate monitoring of circulation, glucose, sodium and potassium and ensure the infusion remains available during transfers. Additional steroid can raise glucose, but that is a reason to adjust glucose management rather than withhold essential replacement.
- 3Once stable and absorbing oral treatment, use the agreed endocrine step-down to oral stress dosing and then usual replacement as recovery permits. Document the reassessment point and avoid leaving a high stress dose unchanged indefinitely or stopping it abruptly.
03SGLT2 safetyPostoperative nausea with apparently reassuring glucoseA patient previously taking an SGLT2 inhibitor develops nausea and rapid breathing after major surgery, with glucose 10 mmol/L.+
- 1Assess physiology, obtain blood ketones and acid–base measurements, and seek urgent senior review. Moderate glucose does not exclude SGLT2-associated ketoacidosis, and abdominal symptoms may overlap with surgical complications.
- 2Withhold the SGLT2 inhibitor and manage confirmed ketoacidosis through the appropriate emergency pathway. Continue investigation for infection, starvation, insulin deficiency and surgical causes rather than assuming the medicine is the only contributor.
- 3For an inpatient, consider restart only after clinical stability, normal eating and drinking, and capillary ketones below 0.6 mmol/L, with an individual review. If DKA occurred during treatment, do not automatically restart without establishing and resolving another cause and obtaining appropriate specialist advice.
05Relevant medicines and safetySpecific regimens and precautions when the skill involves prescribing.
Hydrocortisone: adult adrenal crisis or major surgical stress cover
For suspected adult adrenal crisis, give hydrocortisone 100 mg intravenously immediately, or intramuscularly if IV access is unavailable, then 200 mg by continuous IV infusion over each 24 hours; an alternative is 50 mg IV or IM every 6 hours. For major surgery in established adrenal insufficiency, give 100 mg IV at induction followed by 200 mg/24 hours IV while parenteral stress cover is required. Continue until clinical recovery and specialist-directed transition to oral replacement.Give crisis treatment with appropriate fluid and physiological resuscitation; do not wait for diagnostic confirmation. Monitor glucose, electrolytes and fluid balance, and check product-specific reconstitution. Stress dosing is not required identically for every minor procedure or every brief steroid course. Arrange endocrine-led step-down and continuation of essential long-term replacement.
06Feedback, follow-up and evidenceReview outcomes, seek feedback and identify what to improve.
- Set glucose monitoring frequency for each stage of care and ensure results are acted on. Patients receiving insulin or medicines associated with hypoglycaemia need particularly frequent perioperative review under the agreed pathway.
- Measure capillary blood ketones daily during the perioperative period for people with diabetes using SGLT2 inhibitors until they eat and drink normally. Normal glucose does not remove this requirement; deterioration or abnormal ketones needs prompt clinical and acid–base assessment.
- Check insulin, substrate fluid and steroid delivery after every transfer. Pumps, cannulas and infusion prescriptions can become disconnected from the written plan during otherwise routine movements.
- Before discharge, reconcile the home regimen with actual intake, renal function and recovery. Provide sick-day advice, steroid emergency information where relevant and a clear contact for medication problems.
07Special situationsVariants, exceptions and circumstances that change the usual approach.
SGLT2 timing is guidance-specific
The 2025 UK elective consensus ordinarily omits SGLT2 inhibitors on the day before and day of surgery. For a person with diabetes starting a very low energy or liver reduction diet for surgery, stop at commencement of that diet and adjust the diabetes plan. MHRA requires interruption and blood-ketone monitoring during hospitalised major surgery or serious illness; a symptom-only testing policy is insufficient.
GLP-1 medicines require aspiration assessment
The 2025 UK consensus supports continuation with risk assessment and mitigation, while MHRA highlights aspiration potential during anaesthesia or deep sedation. Drug exposure, gastrointestinal symptoms and the planned anaesthetic matter. Avoid replacing these assessments with an unqualified instruction that every patient must stop for a week.
Diabetes technology needs ownership
A pump or glucose sensor can support care only if the team understands its limitations and responsibility. If the patient cannot self-manage, agree who will supervise or replace the system. Sensor readings may need confirmation with the approved bedside method when treatment decisions or symptoms demand it.
Steroids and glucose interact
A stress-dose steroid regimen can increase insulin requirements during recovery; improving illness and steroid reduction can later lower them. Review the two plans together so that yesterday’s correction strategy does not become tomorrow’s hypoglycaemia.
08Common pitfallsFrequent interpretation and management errors.
- 01
Omitting basal insulin in type 1 diabetes because the patient will not eat breakfast.
- 02
Using a normal or moderately raised glucose to dismiss possible ketoacidosis after SGLT2 exposure.
- 03
Giving an induction dose of hydrocortisone without arranging ongoing cover during prolonged postoperative fasting.
- 04
Stopping an insulin infusion before confirming basal insulin provision and the safe transition back to subcutaneous treatment.