Peri-operative guidelines

The peri-operative managment of diabetes and, in particular, what changes patients are advised to make to their insulin regimen or oral hypoglycaemic agents in the peri-operative period, is a huge challenge. The aim should be to keep blood sugars in an 'ideal range' (6-10 mmol/L) as far as possible, to avoid hypoglycaemia and to avoid prolonged hospital admission associated with surgery.

What level of glycaemic control is acceptable for safe elective surgery?

Most specialists would want to see the HbA1c below 8.5% (69 mmol/mol) prior to routine elective surgery.

National guidelines vs local protocols 

The whole field of peri-operative guidelines for patients with diabetes is contentious and, while the advice here is based on the recently released NHS diabetes national guidelines, it should be used with careful reference to local guidelines, protocols or policies.

What should patients be advised if they take a basal bolus insulin regimen?

Assuming this is a 'standard' basal bolus regimen of long acting insulin at bed time and three times a day prandial insulin then they should be advised to take their normal insulin doses the day before surgery and then on the day of surgery.

If they are on a morning list omit the breakfast and lunchtime doses and return to normal doses at tea time (assuming they are able to eat and drink normally).

If they are on an afternoon list then breakfast dose of insulin should be taken as normal with an early light breakfast, lunchtime dose omitted and tea time dose should be taken as normal if eating and drinking has been resumed.

How should a patient be advised if they take a twice daily biphasic insulin such as Humulin M3, biphasic insulin aspart (Novomix 30) or biphasic insulin Lispro (Humalog Mix 25/Mix50)?

The day before surgery normal doses should be taken. The morning of surgery a half normal dose should be taken. On the evening after surgery normal doses should be resumed.

How should a patient be advised if they take a once daily insulin such as insulin glargine (Lantus), insulin detemir (Levemir), or an isophane insulin such as Humulin I or Insulatard?

If these are taken in the evening, then the day before surgery these should be taken as normal although some centres recommend a precautionary 1/3 dose reduction. On the day of surgery, the normal dose should be taken so long as normal dietary intake has resumed by the evening.

If these are taken in the morning then the day before surgery the normal dose should be taken. On the day of surgery the normal dose should again be taken although in some centres a precautionary 1/3 dose reduction is advised.

How should a patient be advised if they take a DPP-IV inhibitor (Sitagliptin, Saxagliptin or Vildagliptin) or a GLP-1 agonist (Exenatide or Liraglutide)?

They should take medications from these classes of drugs as usual on the day before surgery and omit completely on the day of surgery regardless of whether the procedure is to be on an afternoon list or a morning list.

How should a patient be advised if they take pioglitazone?

This should be taken as normal on the day before and the day of the procedure.

How should a patient be advised if they take gliclazide (or other sulphonylurea)?

The day before the procedure this should be taken as normal. The day of procedure the morning dose should be omitted and, if on an afternoon list, the afternoon dose also omitted.

How should a patient be advised if they take metformin?

The day prior to the procedure this should be taken as normal. The day of procedure this should be taken as normal unless on a tds regimen in which case the lunchtime dose should be omitted. This advice is the same for patients on morning and afternoon lists.

What are the general principles of taking a patient through surgery without variable rate intravenous insulin infusion (VRIII)? 

1. Baseline HbA1c should not be above 8.5% (69 mmol/mol).

2. Total duration of starvation should not mean missing more than one meal.

3. Blood sugars should be checked hourly during the starvation period (including the procedure itself).

4. Ideally blood sugars are kept in the 6-10 mmol/L range but 4-12 mmol/L may be acceptable.

5. Appropriate pre-procedure adjustments to insulin and/or oral hypoglycaemic agent doses are made as outlined in subsequent sections.

6. The patient should resume normal eating patterns as soon as possible post-procedure.

7. The patient should have their procedure carried out early on the surgical list (ideally first).

How does a doctor decide if it is possible to take a patient through surgery without a VRIII?

If surgery is being undertaken as an emergency, if the patient is systemically unwell or if the total duration of fasting is likely to lead to more than one meal being missed, then a VRIII is still necessary.

However, for many patients undergoing elective, and especially day-case, surgery (and other procedures involving starvation), then a protocol involving adjustment of usual diabetes medication (oral hypoglycaemic agents or insulin) and close monitoring of blood sugars is possible - as outlined below.

Should all patients with diabetes be admitted the night before and put on a VRIII prior to surgery?

This practice is no longer a blanket recomendation as VRIII is associated with frequent hypoglycaemia and prolonged duration of admission.

What should patients be advised if they are taking a different insulin regimen not listed above?

Further advice on the less common insulin regimens - such as three times a day biphasic insulin, twice daily intermediate acting insulin and twice daily rapid acting insulin - can be obtained by consulting the national peri-operative guidelines.

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