most current insulin preparations in Australia contain human insulin prepared by recombinant DNA technology. Only Hypurin Neutral and Hypurin Isophane contain insulin of bovine origin.
Protaphane, Actrapid and Mixtard should be given 30min before meals
Ultrarapid insulins such as Humalog, Humalog Mix 25, NovoRapid, and NovoMix 30 should be given immediately with meals 1)
ultra rapid onset and short duration:
glulisine (Apidra), lispro (Humalog) and aspart (NovoRapid) are modified human insulins that have onset and offset after subcutaneous injection that is half that of regular insulin.
glulisine - maximum effect after s/c dose ~60min and effect lasts ~1.5 hours
rapid onset, short duration:
regular/neutral/soluble insulin
maximum effect after s/c dose ~90min and effect lasts some 2.5 hours
often used as a corrective dose, as part of a sliding scale insulin regime, and as iv infusion for Mx of diabetic ketoacidosis (DKA)
eg. Actrapid, Humulin R
intermediate acting suspensions (NOT for iv use):
isophane insulin
Humulin NPH (rbe) - onset of action occurs at ~1hr, with a duration 16-18 hrs and peak at 4-10hrs.
Hypurin Isophane NPH (bovine)
Protaphane (rys)
long acting (NOT for iv use):
these are expensive, cannot be mixed with other insulins and thus require extra injection, and most find they don't last the full 24 hours, but can be given any time of day as long as it is the same time each day.
glargine insulin (Lantus)
lasts for 24 hours and has a very flat profile and thus provides good basal levels of insulin as a daily bolus injection.
for type 2 diabetics: initially 10 Units s/c once a day
detemir insulin (Levemir)
for type 2 diabetics: initially 10 Units or 0.1-0.2 Units/kg s/c once daily
mixed biphasic neutral + isophane insulin suspensions for once daily or bd s/c dosing (NOT for iv use)
Mixtard insulin contains recombinant human insulins (rys) - available as 30/70 or 50/50
Humulin 30/70 - duration of activity of 16-18hrs and peak at 2-12 hrs
mixed biphasic ultra rapid + protamine insulin suspensions for once daily s/c dosing (NOT for iv use)
Humalog Mix25 and Humalog Mix50 - lispro + protamine
NovoMix 30 - aspart + protamine
insulin administration errors
insulin dosing is one of the major causes of medication administration errors
ALWAYS write UNITS and not just IU or U which can be mistaken as 10 or 0 and thus cause a 10x increase in dose
DO NOT use tuberculin syringes as these are labeled differently and can easily result in a 10x increase in dose
name confusion with Humalog and Humulin, Humulin U and Humulin N, and with Insulin Lente and Insulin Lantus.
failure to re-suspend insulin suspensions prior to drawing up - gentle rolling of vial in palm is important for these otherwise one may draw up solution containing only 20 units/ml instead of 100 units/ml. Insulin pens also require this re-suspension prior to use.
pump programming errors
insulin infusion pumps turned off for inter-hospital transfers and then forgetting to be re-started.
computerised prescribing errors
blood glucose measuring device read out design errors which can allow read out to be mistaken (eg. LO may be mistaken as 10)
peri-operative insulin Mx
A reasonable trade off between avoiding hypoglycaemia and possible complications of hyperglycaemia is to aim for an intraoperative blood glucose level of 5 to 10 mmol/L.2)
Using the same principles used in managing blood pressure the important components are first to frequently (at least hourly) measure the blood glucose and not to over treat hyperglycaemia and hypoglycaemia (avoid Alpine BSLs).
5% dextrose can be used to treat hypoglycaemia (2 ml/Kg) intravenously, but can also be given orally.
Hyperglycaemia is treated with corrective doses of insulin.
In the postoperative period the rapid acting insulins are likely to be much better for sliding scales than regular insulin.
diabetic patients need 3 levels of glycaemia control:
basal control
glargine insulin has such a flat profile that patients can take their usual dose before surgery with minimal risk of hypoglycaemia while also avoiding ketosis. This is easier than running a glucose-insulin or glucose-insulin-potassium (GIK) infusion.
glargine, which lasts for 24 hours and has a very flat profile. Glargine provides good basal levels of insulin as a daily bolus injection.
basal insulin can also be provided with continuous insulin pumps using rapid acting insulin such as aspart or lispro.
nutritional
5% dextrose infusion 100ml/hr for fasting adults (higher if BGL falls below 4 mmol/L)
prandial dose insulin for those who are not fasting
corrective
orrective insulin in the operating room can be with regular insulin by the intravenous route that hastens the onset.
subcutaneous rapid acting insulin is an alternative - as an example see Sliding Scale Insulin below
sliding scale insulin (SSI)
NOTE: fasting diabetic patients should have 5% dextrose running at 100ml/hr (higher if BGL falls below 4 mmol/L)
the BGL should be determined 4hrly if fasting, or qid - 30min prior to meals and before sleep (or if features of hypoglycaemia or hyperglycaemia develop) and the s/c dose of regular insulin given according to the scale
those who are not fasting will develop unstable control if doses are not synchronised to be measured 30min before meals 3)
sliding scale insulin using regular insulin is not physiological and does not make clinical sense, indeed, in type 1 patients, is likely to lead to increased instability due to the delayed onset of action.
if a sliding scale is used for corrective Mx, it should be with a rapid acting agent and preferably dosing should be related to total daily requirements as each person will have different insulin sensitivities and these may change during their illness.
it is time we ceased using the traditional regular insulin sliding scale protocols! 4)
example traditional s/c sliding scale insulin for either fasting or oral diet patients, and can be used for type 1 and type 2 patients
NovoRapid insulin is compatible with sodium chloride 0.9% and glucose 5%
infusion should be prepared about half an hour before use, where possible, to allow for adsorption of insulin to the bag to occur and the first 20mL must be run through the line and discarded to saturate insulin binding sites in the tubing
if the infusion is required urgently, the waiting time can be waived, but the infusion rate may need to be increased, depending on the patient’s response.
diluted solution is to be used within 24 hours
check serum potassium level before commencing an insulin infusion.
hypokalaemia must be corrected first to avoid exacerbating hypokalaemia with intravenous insulin.
in general, apart from use in ICU, the concentration for insulin infusions in adults is 100 units of NovoRapid in 100mL of sodium chloride 0.9%
closely monitor blood glucose levels to avoid hypoglycaemia
hourly in the 1st 8hrs then consider reducing frequency if stable
start 5% glucose infusion at 100mL/hr (or 50mL/hr of 10% glucose) once glood glucose < 15mmol/L
cease infusion for 30min if blood glucose falls below 5mmol/L then re-start at lower rate
cease infusion for 1 hour if blood glucose falls below 4mmol/L - also double the rate of IV glucose infusion for next 15 minutes and check blood glucose level every 15min until above 5mmol/L, then re-start at lower insulin infusion rate
check capillary blood ketone level at least once daily
consult tables of how to adjust insulin infusion rate based upon blood glucose levels over past 1-2hrs
various pumps are available and each has a different menu for operation but all use a rapid acting analogue insulin
aims to maintain background basal rate insulin levels supplemented by boluses when food is consumed or to correct an elevated glucose level
the patient must be competent in understanding usage and the pump will need to be managed by others or ceased if they become confused or unable to operate it
usually the patient will perform at least 4 blood glucose level assessments each day if stable - before meals, 2 hours after at least one meal, and before going to sleep (sometimes a 2am measure is needed as well)
cessation of the pump will result in the patient becoming relatively insulin deficient within 1 hour and absolutely insulin deficient within 4 hours