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Introduction
Insulin is a hormone produced by the beta cells in the pancreas, it is released when blood glucose levels are raised for example after a meal. Insulin regulates the amount of glucose in the blood and is required for the body to function normally. Insulin is used to treat people with type 1 and type 2 diabetes and it is estimated that about 20- 30% of people with diabetes are treated with insulin injections. The main side effects of insulin therapy are hypoglycaemia (low blood glucose) and lipohypertrophy (fatty lumps which develop at injection sites).
Monitoring of blood glucose is vital in people with diabetes who are in hospital as acute illness or surgery can cause the blood glucose levels to rise and insulin doses may need to be reviewed.
Insulin is frequently included in the list of top ten alert medicines and insulin errors have been identified as an important cause of hospital admission. From 2003 – 2009 the National Patient Safety Agency (NPSA) identified 15,227 incidents, including 6 deaths, involving insulin.
The most common insulin errors are:
the wrong type of insulin being prescribed / given
the wrong dose of insulin being prescribed / given
Insulin doses being given at the wrong time or omitted.
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The Right Insulin - Types of insulin
In the UK there are currently over 20 different insulins. Many have similar sounding names such as Novorapid and Novomix 30. However these insulins differ in how quickly they act and how long they act for and serious consequences can occur if the wrong insulin is prescribed and given in error.
Insulin is generally defined by how quickly it acts and how long it acts for. Most insulin in current use is human or modified human (analogue) insulins, however animal insulin (Pork and Beef) are available. The main types of insulin are:
Human Insulin
Rapid acting insulin* e.g. Novorapid, Humalog
Short acting insulin e.g. Actrapid, Humulin S, Insuman Rapid
Medium acting insulin e.g. Insulatard, Humulin I, Insuman Basal
Long acting insulin* e.g. Lantus. Levemir
Pre-mixed insulin (a mixture of short and intermediate acting insulins) e.g.
Humulin M3, Humalog Mix 25, Humalog Mix 50. These insulins vary in the amount of short acting and long acting insulin they contain e.g. Humulin M3 contains 30% short acting and 70% intermediate acting insulin
Animal Insulin
Short acting insulin e.g. Hypurin Porcine Neutral, Hypurin Bovine Neutral
Medium acting insulin e.g. Hypurin Bovine Isophane, Hypurin Porcine Isophane
Pre-mixed insulin (a mixture of short and intermediate acting insulins) e.g.
Hypurin Porcine 30/70 Mix
*These insulins are analogue insulins
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The Right Insulin - time action profiles of different insulins
It is important to know how fast insulin acts and how long it lasts as this can influence when it is best to give the insulin injection.
Type of insulin Onset of action
Peak action Duration of action
When to inject
Rapid acting 10-15 minutes
2 hours 4 hours Just before eating
Short acting 20-30 minutes
2.5 hours 4-6 hours 20-30 minutes before food
Medium acting 30-45 minutes
8-10 hours 18-20 hours Usually given with food if prescribed twice daily and can be given either with breakfast or before bed if prescribed once a day (times should be consistent) Long acting
insulin
3-4 hours No peak action
Up to 24 hours Lantus can be given once a day (at the same time) irrespective of food
Levemir can be given once or twice a day (at the same times) irrespective of food Pre-mixed insulin
e.g. Humulin M3, Insuman Combi 15, Insuman Combi 25, Insuman Combi 50 and Hypurin Porcine 30/70.
20-30 minutes
2-4 hours 18-20 hours 20-30 minutes before food
Pre-mixed anologue insulin e.g.
Novomix 30, Humalog Mix 25, Humalog Mix 50
10-15 minutes
2 hours 18-20 hours Just before a meal
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The Right Device
Insulin is available in 10ml vials (for use with insulin syringes), in cartridges (for use with cartridge pens only) and in prefilled pens. Not all insulins are available in all of these forms.
Insulin Syringes:
Insulin syringes are specifically designed for drawing up and giving insulin. The markings on the side are specific for units of insulin. Insulin must never be drawn up and given with a standard syringe as this can lead to an overdose of insulin.
In line with the 2010 EU directive on safe sharps the trust now uses BD SafetyGlide 0.5 ml Safety Insulin Syringe to draw up and administer insulin.
Insulin should only be drawn from insulin vials and not 3ml cartridges or pre-filled pens. Insulin vials are for single patient use. The vial should be labelled with the date of opening, the patients name and hospital number.
The only exception to single patient use is the Actrapid vial being used for preparation of Glucose-Potassium-Insulin (GKI) regimens. In this case the vial can be used for multiple patients but it must be annotated with the date of opening and discarded after 28 days.
Cartridges for Insulin Pens:
Insulin cartridges can only be used with the specific insulin pens for which they have been designed. Cartridges are not interchangeable between pens for example
Novomix 30 insulin cartridges can only be used with a Novopen. Insulin must not be drawn out of a cartridge with an insulin syringe as this can make the insulin unstable and lead to air bubbles in the cartridge..
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The Right device (continued)
Prefilled Insulin Pens:
Prefilled insulin pens have the insulin incorporated in to the pen. They cannot be refilled and are therefore disposed of when empty.
Insulin must not be drawn out of a prefilled pen with an insulin syringe as this can make the insulin unstable and will cause damage to the pen which may contaminate the insulin.
Insulin Pen Needles :
Cartridge pens and prefilled insulin pens require a disposable insulin pen needle for insulin delivery. Insulin pen needles come in a variety of sizes 5mm, 6mm or 8mm.
At Aintree Hospital patients giving their own insulin should use BD micro-fine 5mm pen needles. When insulin is being given by staff BD Autoshield Duo 5mm Safety Pen Needles must be used . A new pen needle must be used for each injection and used needles must be discarded into a sharps box.
Insulin Pumps:
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Insulin pumps are becoming a common method of insulin delivery in people with type 1 diabetes. Insulin pumps deliver short or rapid acting insulin, via a cannula, into the subcutaneous tissue on a continuous basis. Bolus doses of insulin need to be given via the pump to cover the rise in blood glucose levels caused by meals.
Insulin pumps contain rapid / short acting insulin. If the pump is disconnected the patient will become deficient of insulin very quickly and is at risk of developing Diabetic Ketoacidosis. If the patient is not able to manage the pump then
subcutaneous insulin must be given.
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The Right Dose
Before giving an insulin injection always check the dose with the prescription chart and the patient. Abbreviations should never be used when prescribing insulin or documenting changes to the dose in the patients case notes. Abbreviations can lead to a fatal overdose e.g. 8U can be mistaken for 80 units of insulin.
Copies of the patient’s repeat prescription from the GP do not include the dose of insulin but do state the formulation e.g Novorapid Penfill cartridge 100units / ml- this refers to the strength of the insulin and not the dose.
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The Right Way and the Right Time
Insulin should be injected at a 90 degree angle into subcutaneous tissue. Insulin injection sites include the upper outer thigh, abdomen and buttocks. Injection sites should be rotated to avoid the development of lipohypertrophy.
Pre-mixed insulin and medium acting insulin (cloudy) should be re-suspended prior to injecting.
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dialling up the correct dose to ensure that the pen is working. A new pen needle should be used for every injection. Pen needles should be disposed of in a sharps box.
Some insulins need to be given in relation to food e.g. rapid, short and premixed insulin.
Timing is crucial if insulin is to be effective e.g. if a patient is prescribed once daily long acting insulin then this should be given at approximately the same time each day.
Always check the expiry date before injecting insulin.
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Side Effects of Insulin
The 2 most common side effects of insulin are hypoglycaemia (low blood glucose, less than 4mmol/litre) and lipohypertrophy (fatty lumps).
Hypoglycaemia:
Common causes of hypoglycaemia include: too much insulin, not enough to eat, poor appetite due to illness, increased activity or a late or missed meal.
Signs and symptoms of hypoglycaemia include:
Pallor, tremor and sweating
Nausea, palpitations and feeling anxious
Slurred speech, confusion , loss of concentration and drowsiness If left untreated hypoglycaemia can lead to loss of consciousness and seizures.
Guidelines for the management for hypoglycaemia are available on the intranet- from the home page of the intranet click on Trust Documents and then enter hypoglycaemia into the search box.
If a patient has an episode of hypoglycaemia then the hypoglycaemia should be treated and blood glucose repeated to ensure that it is rising. Insulin should not be omitted. If episodes of hypoglycaemia are frequent or a pattern is noted then a review of insulin dose is needed.
Lipohypertrophy:
Lipohypertrophy is the development of fatty lumps at injection sites and is usually due to injecting repeatedly in the same area. Lipohypertrophy is unsightly and can interfere with the rate of insulin absorption leading to erratic blood glucose levels.
Injection sites should be examined on a regular basis and if lipohypertrophy is found the patient should be advised to rotate the injection sites. In addition consideration should be given to reducing the insulin dose as the insulin may be absorbed more quickly when the sites are changed.
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Intravenous Insulin
IV insulin is used to treat patients with:
Diabetic Ketoacidosis (DKA)
Hyperosomolar Hyperglycaemic State (previously known as HONK – hyperosmolar non-ketotic state)
Patients who are nil by mouth or fasting for a procedure
Patients with hyperkalaemia (high potassium)
IV insulin may be prescribed as a GKI or a variable rate insulin infusion. Intravenous insulin only lasts between 5-8 minutes therefore if the cannula tissues or the pump runs out, the patients blood glucose will start to rise very quickly and DKA can develop. Therefore the cannula must be replaced or the pump refilled very quickly.
If Lantus or Levemir or Tresiba insulin are part of the patient’s usual insulin regimen and the patient needs a GKI or a variable rate insulin infusion the Lantus or Levemir insulin must still be prescribed and given when the patient is on the IV insulin
regimen. Both of these insulins are long acting. If they are stopped blood glucose can be difficult to control when the IV insulin is stopped. Subcutaneous insulin must be given 30 minutes before IV insulin is stopped to ensure that the patient has some insulin in their system.
Further information can be found on the intranet - from the home page of the intranet click on Trust Documents and then enter GKI into the search box.
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General Points about Insulin
Unopened insulin should be stored in a fridge between 2 and 8 degrees. Insulin should not be frozen as this can alter the efficiency.
Insulin should not be left in direct sunlight- this will alter its effectiveness.
Once opened, insulin does not need to be stored in the fridge but should be kept at room temperature and discarded after 28 days.
Before using insulin check the appearance to ensure that there are no particles in the solution.
An ‘Insulin Passport’, which is a record of the type and formulation of the insulin the patient is prescribed, should be issued to all patients who are started on insulin in hospital or if the type of insulin is changed during their hospital admission.
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Get your prescription right
Correct insulin
type
Correct Insulin
dose
Correct time of dose
Good blood Glucose
