Management of insulin treated diabetes during surgery
The chief principle of diabetic management through any crisis
in which patients cannot eat or drink for any reason is to
continue insulin administration.
The best method is to give the insulin by continuous intravenous infusion either by infusion
pump or directly from the drip bag.
For operations in which a patient is likely to be maintained
on a drip for more than 12 hours a regimen is needed which can
be continued for an indefinite period.
Again there are two methods of administering the insulin: a variable rate infusion
using a pump, or if this is not available, a glucose insulin-infusion.
Note:
• The rate of intravenous infusion must depend on the clinical
state of the patient with regard to the volume depletion,
cardiac failure, age, etc.
• Potassium replacement is required.
• If the blood glucose is persistently above 10 mmol/l the
infusion should be changed to 0·9% saline.
• Blood glucose should be monitored every one to two hours
during surgery and regularly postoperatively.
• Try to maintain the blood glucose concentration in a safe
range—6·0-12 mmol/l.
• Regular (at least daily) electrolyte measurements are required.
After recovery: changing to subcutaneous insulin
Once the patient starts to eat and drink conversion back to
subcutaneous insulin injections is undertaken as follows.
• Always change to subcutaneous insulin before breakfast and
never in the evening so that adequate supervision can be
assured.
• Stop the insulin pump 30 minutes after the first
subcutaneous insulin injection.
• Insulin regimen and dose: if the previous regimen is known
then this should be given; if the patient is still in bed or
unwell the total dose may need to be 10 to 20% more than usual.
If the patient was not previously taking insulin,
predicting the requirement is not easy and the amount needs
adjustment from day to day.
Initially use insulin 30-40 units
daily in divided doses given four times daily.
Patients with hyperglycaemia often relapse after conversion
back to subcutaneous insulin. When this happens there are
three possible approaches.
• Give additional doses of soluble insulin at any of the four
injection times (before meals or bedtime).
• Add an intravenous insulin infusion temporarily while
continuing the subcutaneous regimen until the blood
glucose concentration is satisfactory.
• Revert completely to the intravenous regimen, especially if
the patient is unwell.
Surgery in Type 2 diabetes
Management of diabetic patients treated with diet or oral
hypoglycaemic agents is more straightforward, so long as the
diabetes is well controlled.
If the random blood glucose value is less than 12 mmol/l:
• omit the tablet on the day of surgery
• check the blood glucose concentration before and soon after
the operation; if the blood glucose value is more than
12 mmol/l start soluble insulin.
If the diabetes is poorly controlled (random blood glucose
greater than 12 mmol/l)
Management of insulin treated diabetes during day surgery
Patients with insulin treated diabetes requiring an anaesthetic
for relatively minor operations or investigative procedures
(for example, barium radiological examinations, cystoscopy,
endoscopy, etc.) can be treated as day cases without hospital
admission provided that:
• the procedure is undertaken in the morning first on the list
(if the procedure is performed first on an afternoon list, a
light breakfast is taken after half the normal insulin dose,
followed by regular blood glucose monitoring)
• the procedure does not exceed approximately one hour in
duration
• the patient will be able to eat and drink within one hour of
the procedure
• the patient is able to self-monitor blood glucose and adjust
insulin appropriately.
The blood glucose should be rechecked before discharge. If
significant problems with diabetes control persist, then hospital
admission may be required after all.
