Figure 1:- Which Regime for my Patient?

1. Decide on the type of surgery

   • Minor- patients expected to eat and drink within 4 hours of operation
   • Major- all other patients
2. Then, is the patient Insulin or Non-insulin dependent ?

3. Finally, are they:-

   • poorly controlled: delay surgery and change to soluble insulin three times daily but if surgery urgent, use Major surgery regime
   • well controlled: use the appropriate regime from the Major or Minor

General Measures for all diabetics:

Measure random sugar preoperatively

• 4 hourly for IDDM
• 8 hourly for NIDDM

Test urine 8 hourly for ketones and sugar

Place first on operating list

Aim for a blood glucose of 6 - 10mmol/l 

Figure 2:- Minor Surgery

Non insulin Dependent Diabetics

Insulin dependent Diabetics

This regime only suitable for patients whose random sugar is < 10 mmol/l on admission, will only miss one meal preop & are first on the list for very minor surgery eg cystoscopy

Preoperatively	Normal medication
Day of operation	No breakfast, no insulin, place first on list. Blood glucose- 1 hour preop and at least once during op (hourly if op > 1 hour long) postop - 2 hourly until eating then 4 hourly
Postoperatively	Restart normal S/C insulin regime with first meal.

Figure 3:- Major surgery

• All insulin dependent and non-insulin dependent who are poorly controlled (blood glucose >10mmol/l) (many NIDDM become insulin dependent during major surgery and will need managing as such. Regular glucose measurements will detect this).
• Normal medication until day of operation

Day of operation

Omit oral hypoglycaemics and normal subcutaneous (S/C) insulin

Blood glucose - check blood sugar(and potassium) 1 hour preop then 2 hourly from start of infusion at least once during operation (hourly if op > 1 hour long) at least once in recovery area 2 hourly post operatively

Regime 1 - no infusion pump available.

Start intravenous infusion of 5 or10 % dextrose (500 ml bags) over 4 - 6 hours and add Insulin and Potassium Chloride (KCl) to each 500 ml bag as below. Change bag according to blood sugar level readings:-

Postoperatively

• Non-insulin dependent
  • - stop infusion and restart oral hypoglycaemics when eating and drinking
• Insulin dependent
  • - stop infusion when eating and drinking
  • calculate the total daily dose (units) of insulin the patient was taking preoperatively
  • give this as S/C Soluble insulin (Actrapid), divided into 3 - 4 doses in 24 hours
  • this may need to be adjusted up or down until blood sugar levels stable.
  • once stable restart normal regime

Remember that the patient may need additional fluids depending on surgery, blood loss etc. 

Figure 4:- Major surgery - alternative regime

Regime 2 - for use with infusion pumps

The insulin and dextrose infusions are given via separate infusion pumps. This allows better control than regime 1, but care is needed to ensure the separate lines do not become blocked, or that one infusion runs out leaving the other infusing alone.

Insulin infusion - 50 units insulin made up to 50 ml with saline (i.e. concentration is 1 unit per ml)

• If it is proving difficult to reduce the blood sugar level, then consider increasing the rate of insulin for each glucose level or also giving a bolus of Actrapid of 3 - 5 units.
• Patients normally on higher doses of insulin will need higher rates of insulin infusion.
• Dextrose infusion - 5 or 10 % dextrose infused at 100 ml per hour. Add 10 mmol KCl to each 500 ml of solution.
• Post op - follow instructions as in figure 3. 

Figure 5:- Treatment of Diabetic Ketoacidosis

Aims-

• rehydration (water and salt)
• lower blood sugar
• correction of potassium depletion

Start an intravenous infusion of 0.9 % saline as follows-

Up to 6 -8 litres of fluid may be required or more. Use clinical signs BP, heart rate, CVP, conscious level to judge the amount.

Give soluble insulin (Actrapid) intramuscularly (IM) as follows-

• 20 units IM first dose then 6 units IM hourly
• measure the blood glucose hourly
• when the blood glucose is below 15 mmol/l, change to 6 units IM every 2 hours.

Once the patient has recovered and is eating/drinking, change to S/C insulin.

Potassium (K⁺) supplementation will be required-

There may be a high blood potassium initially, but this will fall as the sugar level comes down.

Measure the potassium hourly. Put 10 mmol K⁺ in the first litre of saline then 10 - 40 mmol in subsequent litres of fluid, depending on the plasma level (normal 3.5 - 5.0 mmol/l).

If potassium measurements are unavailable then put 10 mmol KCl in each litre of fluid.

Other measures- 100 % O2. Blood gas estimation-if pH < 7.10, give 50 mmol of 8.4% bicarbonate. Usually acidosis will correct itself slowly as the sugar comes down. Emergency surgery can start once the rehydration and lowering of blood sugar is underway.