Diabetes and Surgery/Acute Illness

General Advice

  • Ideally patients with diabetes should be placed first on the theatre list (so to avoid prolonged fasting)
  • Ideally patients should have good control of their blood glucose and their HbA1c should be within normal range
    • I.e. pre-prandial: 4-6mmol/l; <12mmol/l post-prandial; HbA1c <8.5%/69mmol/mol
    • If not, it may be necessary to admit a patient early to control blood glucose prior to operating
  • Try to avoid glucose containing infusions

Patients managed with diet alone

  • Monitor capillary blood glucose (CBG) every 2 hours from admission pre-, intra- and post-operatively
    • If <4mmol/l- manage as hypoglycaemia and inform surgical/anaesthetic team
    • If >12 (or 15 depending on area) mmol/l- consider the need for IV insulin and fluids and inform anaesthetic/surgical team
  • Recommend diet/fluids post-operatively ASAP

Patients managed with oral hypoglycaemics

  • If the patient is on the morning list (i.e. missing one meal)
    • Usual medications the day before surgery
    • Omit breakfast and all hypoglycaemics on the morning of the procedure and allow water up to 2hrs pre-operatively.
    • Check BM on admission and 2 hourly
      • If between 4 and 12 mmol/l, no further actions
      • If >12mmol/l, consider variable rate insulin infusion or a one off dose of short acting insulin and monitor BM hourly
    • Restart oral hypoglycaemics with first meal post-operatively
  • If on the afternoon list (i.e. missing >1 meal)
    • Light breakfast may be allowed but still omit oral hypoglycaemics (then as morning list)
    • Alternatively, start VRII and fluids
  • A note about metformin-
    • If the patient is receiving any IV dye/contrast, metformin should ideally be omitted before this.  Similarly, before restarting metformin, ensure the patient has no evidence of hypoxia, volume depletion, cardiac failure or renal impairment (creatinine <150umol/l)- to avoid lactic acidosis.

Patients on insulin

  • Day before- take normal insulin and oral hypoglycaemics
  • If the patient is on the morning list-
    • Omit breakfast short acting or pre-mixed insulins and tablets the morning of surgery
    • If the patient takes a long acting insulin in the morning- half the usual dose may be given in the morning
    • Monitor BMs on admission and every 1-2 hours
      • If between 4 and 12 mmol/l, and the procedure is a minor one (with short duration/quick recovery) then there may not be a need for VRII
      • If >12mmol/l, IVII is recommended
    • If the procedure is a major one- i.e. missing more than one meal- VRII should ideally be started the morning before surgery alongside their longacting insulins
    • Restart short acting insulin with next meal or, if taking premixed insulins, give half the normal dose at lunch

NB For any patients started on IVII, serum potassium should be monitored and potassium included in fluids

Variable Rate IV Insulin Infusion

  • Usually prescribed on an insulin prescribing sheet but MUST ALSO be written in the kardex
  • Usually composed of 50 units of Human soluble insulin e.g. Actrapid or Humalog, in 49.5mls 0.9% saline (i.e. 1 unit per ml)
  • Patients should also be given fluids (0.45% saline + 5% glucose +/- 0.15% or 0.3% KCl at a rate of 100ml/hour)
    • Depending on U&Es patients can be given more or less KCl or more concentrated saline (e.g. 0.9% if hyponatraemic)
    • Give through the same cannula as the insulin infusion (Y-connector)
    • The patient may require extra/less fluids depending on clinical state e.g. patients with cardiac failure could instead get 10% glucose mixture at 50ml/hour i.e. keeping glucose intake the same.
  • The infusion should not be stopped until after the patient has restarted insulin/oral hypoglycaemics
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