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Family Health Magazine
DIABETES

Injecting Insulin
Syringes or pens... which are right for you?

If you need to inject insulin, you want to choose the delivery device that is right for you. Two types are available – insulin syringes and insulin pens.

Syringes

When insulin is supplied in a vial, a syringe must be used. Before each injection, insulin is drawn from the vial into the syringe. A number of companies make these syringes, which come in three different sizes: 3/10 cc, ½ cc, and 1 cc.

When choosing a syringe, knowing how much insulin you require at one time is important. Using a smaller volume syringe ensures the accuracy of your dose.

• 3/10 cc syringes are marked in one-unit intervals, ideal for doses under 30 units.
  
• ½ cc syringes are marked in one-unit intervals, for doses between 30 to 50 units.
  
• 1 cc syringes are marked in two-unit intervals, and are meant for doses over 50 units.

Shorter needles are now available. Such needles are thinner and finer than on regularly sized syringes. Shorter needles may not be appropriate for everyone, especially those on the heavier side. In this case, insulin may not reach the subcutaneous layer of the skin. Always speak to your diabetes educator or pharmacist before deciding which needle length is suitable for you.

Insulin pens

An insulin pen is a device that allows you to inject insulin with greater ease. Insulin pens can hold a 3 mL cartridge of insulin at one time. The pen consists of a cartridge holder, a tip to attach a pen needle, a plunger that pushes the insulin forward when insulin is dialed, and a window where you can see the insulin.

Two types of insulin pens are available: reusable and prefilled insulin pens.

Once the insulin in a cartridge has been used up, the reusable insulin pen can be refilled with a new cartridge. With prefilled insulin pens, the cartridge holder cannot be removed from the insulin pen and so it cannot be refilled. The device may be disposed of in the regular garbage after the needle is removed and placed in a sharps container. Four companies currently make insulin pens: Novo Nordisk, Lilly, Owen Mumford, and Sanofi Aventis.

The Novo Nordisk Pen® 3 can inject up to 70 units of insulin at one time. It comes in blue and silver. Each unit is marked with even numbered units in bold to make them easier to see. All brands of insulin pen needles (also called pen tips) will fit this pen. If too much insulin is dialed, the pen can be dialled back. Before a new cartridge can be put in, the piston on the pen must be dialed back to allow the cartridge to fit. Only the Novo Nordisk 3 mL insulin cartridges fit this pen. For those who use Novo Nordisk insulin, pens are provided free of charge through the pharmacy or doctor’s office. This pen is currently being discontinued and is available only while supplies last.

The Novo Nordisk Pen® 4 comes in blue or silver and can inject up to 60 units of insulin at one time. Each unit is marked with even numbered units in bold so they are easier to see. All brands of insulin pen needles fit this pen. Again, it can be dialed back if too much insulin has been specified. Only Novo Nordisk 3 mL insulin cartridges fit the Novo Nordisk Pen 4. A magnified window and an inner mechanism allow users to both see and hear the number of units dialed. Numbers on the cartridge holder are in bold as well. There is no need to dial back the piston when putting in a new cartridge. A gentle push of the finger will bring the piston into position. The pen is available at no cost through local pharmacies, diabetes centres and doctors.

Novo Pen Junior® comes in orange and green. This pen holds up to 35 units of insulin at one time. Each ½ unit and full unit is marked. All brands of insulin pen needles (also called pen tips) will fit this pen. If too much insulin is dialed, the pen can be dialed back. Before a new cartridge can be put in, the piston on the pen must be dialed back to allow the cartridge to fit. Only the Novo Nordisk 3 mL insulin cartridges fit this pen. For those who use Novo Nordisk insulin, pens are provided free of charge through the pharmacy, doctor’s office or the diabetes education centres.

The Lilly HumaPen® can inject up to 60 units of insulin at a time and comes in teal or burgundy. Each unit is marked, with even numbered units in bold for easier viewing. All brands of pen needles (or pen tips) will fit. The pen can be dialed back if too much insulin is dialed. Only the Lilly brand of 3 mL insulin cartridges fit the HumaPen. However, the HumaPen is currently being discontinued.

The Lilly HumaPen® Luxura™ can inject up to 60 units of insulin at one time, and comes in burgundy and champagne. The first 10 units are all individually marked. After that, units are marked in two-unit intervals. Like the HumaPen, dialling back is possible on this pen, and only the Lilly brand of 3 mL insulin cartridges will fit. The dose window is magnified, making the number of units dialled easier to read. It is also possible to hear the number of units dialled. This pen is not free, but new users of Lilly brand insulin can receive the HumaPen Luxura at no charge from their local pharmacy. Otherwise, the cost is about $90.

The Autopen® 24 is made by Owen Mumford. It comes in two different colours and two different unit capacities. This pen only works with the Lantus 3 mL insulin cartridges, though all pen needles (pen tips) fit. Green pens hold one to 21 units, and dial insulin in one-unit intervals to a maximum of 21 units. Blue pens hold one to 42 units and can only dial insulin in two-unit intervals up to 42 units. This pen cannot dial back if an overdose of insulin is in place. It is then recommended to fully expel the misdialed dose and redial the required dose.

The Lantus® SoloSTAR™ can dial up to 80 units of insulin and comes only in grey. This is a prefilled disposable insulin pen. Each unit is marked, with even numbers in bold for easier viewing. All brands of pen needles fit. This insulin pen can be dialed back if too much insulin is dialed. Sanofi Aventis makes both Lantus insulin and the SoloSTAR insulin delivery device.

Using an insulin pen

All insulin pens must be primed to be sure that insulin is flowing out of the pen needle before an injection.

A pen may need to be primed several times to get insulin flowing. Each insulin pen company has its own instructions about priming. Please refer to the instructions that come with your particular insulin pen. Remember:

• Do not share your pen or needles with anyone. A number of illnesses carried in blood can be transmitted this way, such as HIV and some hepatitis infections.
  
• The insulin pen containing the insulin that you are currently using should not be stored in the refrigerator. Insulin should be at room temperature before injection. Cold insulin may be more painful when injected and may also be absorbed more slowly. All extra insulin penfills should be stored in the refrigerator until needed.
  
• Do not store pens with a needle attached, as the needle may trap air and contaminate your insulin.
  
• Use a new pen tip for each injection.
  
• Used tips can bend and not deliver the correct dose of insulin. Pen tips are very fine and are meant for only a single use.
  
• Remove the pen tip after every injection. This ensures a fresh pen tip is used every time an insulin injection is done.
  
• Always have a back up for insulin, pen needles and syringes, in case your regular pen does not work properly or is lost or damaged.

Insulin pen needles

Currently three companies make the pen tips: BD, Novo Nordisk, and Owen Mumford. Insulin pen tips come in variety of gauges (thickness) and lengths.

Five or six mm pen needles are generally recommended for children and smaller people with low to moderate body fat who want the shortest pen needle available. These pen needles can be used with any insulin pen. There is no need to pinch the skin when injecting insulin with these needles.

The eight mm pen needle tips are most commonly used. These work best with skin pinched when injecting the insulin.

The 12 mm or 12.7 mm pen needle tips are recommended for those who take large doses of insulin and have dexterity problems with their hands. Skin does need to be pinched when injecting insulin with these needles.

Syringes and pen needle tips are only meant for one time use. A silicone coating on syringes and pens tips ensures smooth and easy injections. Using a syringe or pen tip over and over will cause more pain. Insulin can be contaminated when puncturing the rubber stopper on the insulin vial if air is allowed into the vial or cartridge. If too much air is allowed into the insulin cartridge, it can also mean inaccurate doses.

Advances in technology are allowing thinner and finer syringes and pen tips. Repeatedly using syringes and pen tips can mean that at some point the needle may break, possibly leaving fragments of metal in the skin.

If you use two different types of insulin at one meal, insulins that can be safely mixed can be combined in a syringe but not in an insulin pen. With an insulin pen, two injections may be needed to get each kind of insulin. Always check with your nurse educator or pharmacist on how to combine doses.

Disposing of syringes and pen needles

Check with your local pharmacy about proper disposal. Ask if the pharmacy has a program to accept used sharps.

Never throw used lancets, syringes, or pen needles in the regular garbage. These items must all go in an approved sharps container. Such containers display a biohazard symbol, showing approval from the health department.

When disposing of used sharps, do not overfill the sharps container. Only fill to the line indicated on the container. Once full, seal the lid securely, place in a plastic bag and take it to your local pharmacy. Do not put used sharps in coffee cans, bleach bottles or glass jars, as most pharmacies will not accept used sharps in anything other than approved sharps containers. Keep all sharps containers away from children and pets.