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Insulin before surgery...the simple ,practical approach..

Long-acting insulins

Long acting insulins have a relatively peakless profile and, when properly dosed, should not result in hypoglycemia when a patient is fasting.
Preoperatively, the patient should take it as close as possible to the usual time of injection. This could be at home either at bedtime the night before surgery or the morning of surgery. If there is concern for hypoglycemia, the injection can be given when the patient is at the hospital.

• If the patient does not tend to have hypoglycemic episodes and the total daily basal insulin dose is roughly the same as the total daily mealtime (prandial) dose (eg, 50% basal, 50% prandial ratio), the full dose of basal insulin can be given.

Example: If the patient is on insulin glargine 30 U at bedtime and insulin lispro 10 U with each meal and does not have hypo- glycemic episodes, then insulin glargine 30 U should be taken at bedtime.

If the patient has hypoglycemic episodes at home, then the basal insulin can be reduced by 25%.
Example: If the patient is on insulin glargine 30 U at bedtime and insulin glulisine 10 U with each meal (appropriate proportion of doses, similar to the example above) but has hypoglycemic episodes at home on this regimen, then only 22 U of insulin glargine should be taken at bedtime.

If the patient’s regimen has disproportionately more basal insulin than mealtime insulin, then the total daily doses can be added and half can be given as the basal insulin.
Example: If the patient is on insulin detemir 30 U every morning at 6 am and insulin aspart 6 U with each meal and has no hypoglycemic episodes, then 24 U of insulin detemir should be taken in the morning (ie, half of the total of 30+6+6+6).

if the basal insulin is intermediate acting

The intermediate-acting insulin neutral pro tamine Hagedorn (NPH) is usually given twice a day because of its profile
• On the night before surgery, the full dose of NPH insulin should be taken, unless the patient will now skip a nighttime meal because of taking nothing by mouth, in which case the dose can be decreased by 25%.
• On the morning of surgery, since the patient will be skipping breakfast and probably also lunch, the dose should be reduced by 50%.

premixed insulins

Premixed insulins (70/30, 75/25) are a combination of intermediate-acting insulin and either fast-acting or short-acting insulin. In other words, they are combinations of basal and prandial insulin. Their use is thus not ideal in the preoperative period.

There are two options in these situations.

One option is to switch to a regimen that includes long-acting insulin. If the patient is admitted for surgery, then the hospital staff can change the insulin regimen to long acting basal insulin. A quick formula for conversion is to add all the premixed insulin doses and give half as basal insulin on the morning of surgery, similar to the scenario above for the patient with long-acting basal insulin that was out of proportion to the prandial insulin injections.

For example, if the usual regimen is insulin 70/30 NPH/Regular, 60 U with breakfast, 30 U with dinner, then the patient can take 45 U of insulin glargine (which is half of 60 + 30) in the morning or evening before surgery.

Another option is to adjust the dose of premixed insulin. Sometimes it is not feasible or economical to change the patient’s premixed insulin just before surgery. In these situations, the patient can take half of the morning dose, followed by dextrose containing intravenous fluids and blood glucose checks.

Prandial insulin—given before each meal to cover the carbohydrates to be consumed— should be stopped the morning of surgery.

Vann Ma. Perioperative management of ambulatory surgical patients with diabetes mellitus. Curr Opin An- aesthesiol 2009; 22:718–724.
Meneghini lF. Perioperative management of diabetes: translating evidence into practice. Cleve Clin J Med 2009; 76(suppl 4):S53–S59.

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