Insulin Syringes

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1. What size syringe do you need?
2. What length needle to use?
3. What thickness needle to use?
4. Do you intend to reuse your syringe?
Pre-filled syringes.
Who makes insulin syringes?
Advantages of using a syringe.
Disadvantages of using a syringe.
Disposal of used syringes.

How the syringe works.

Basically a syringe is divided into a number of parts. First there is the tube, or barrel, into which a plunger fits. At one end of the barrel is a hollow needle. Along the barrel are calibrations, which indicate the volume of the syringe. Generally the syringe is graduated in millilitre (ml) or cubic centimetre (cc) units.

When the plunger is pulled back a vacuum is created within the barrel and the liquid is sucked up into the barrel. That liquid is expelled when the plunger is depressed.

Something you need to know.

To understand about insulin syringes you need to know a bit about insulin itself, so bear with me.

Insulin is measured in units. The most common is U100, which has 100 units of insulin in 1 millilitre (ml) (1 cubic centimetre (cc) )of solution.

To inject U100 insulin you must use a U100 syringe. This syringe usually has an orange needle cover and black graduation markings.

There is also a U500 insulin, which has 500 units of insulin in 1 millilitre (ml) (1 cubic centimetre (cc) )of solution.

This is rare, used mainly by people with a high degree of insulin resistance and who take more than 200 units a day. It would obviously require a U500 syringe.

Occasionally a person uses both the above types of insulin and in that case they need to be very careful to use the right syringe with the particular type of insulin. Muddling them up could be fatal.

There is also a U40 insulin, a weaker dilution with each ml (cc) containing 40 units of insulin.

This is often the insulin used for pets.

This is not available in the US but can still be found in other countries, so if you are travelling about and need to buy insulin and syringes be careful which you get. If you normally use U100, injecting U40 will send your blood glucose way up. This also means you will have to pay attention to any syringes you buy as they may be for U40, not U100.

These U40 syringes have red needle caps and red graduation markings.

How do syringes differ and which syringe to use?

Syringes are not all the same. They can vary in needle length and gauge, barrel capacity and type of graduation. You want to find the one best suited to your needs. For instance you need to consider the following:-

1. What size syringe do you need?

Syringes are manufactured in
25 unit (0.25ml or 1/4 cc) (rarely),
30 unit (0.3ml or 3/10 cc),
50 unit (0.5ml or 1/2 cc) and
100 unit (1.0ml or 1cc) measures.
Which one you use will depend on how much insulin you inject at one time. You need to try and match your syringe to your insulin dose.

The 100 unit syringe is usually graduated in
2 unit increments (2, 4, 6, 8, 10),
though there are some that are marked in
1 unit increments (1,2,3,4,5,6,7,8,9,10).
If you take more than 50 units of insulin at a time this is the syringe for you.You can, if anybody is crazy enough to even consider doing this, divide your dose between two 50 unit syringes and give yourself two injections - but why would you want to?

The 50 unit syringe, which is sometimes called the 'low dose' syringe, has 1 unit graduations. This is your average syringe and is better for odd-number doses, i.e. 47 units, than the 2 unit graduated 100 unit syringe where you would more or less have to guess the position for the odd unit.

The 30 unit syringe may be graduated in either 1-unit or 1/2- unit markings.

This smaller syringe has markings that are wider apart so it is easier to read, a useful attribute if you have vision problems.

The one with 1/2 unit markings is great for children or adults who are using very small doses of insulin.
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2. What length needle to use?

Needles come in assorted lengths, though there are two common ones.

The standard length is 1/2 an inch (12.7mm) while what are termed short needles are usually 5/16 (8mm).

The thinner the needle the shorter they usually are because then they do not bend so easily.

The short needle has an advantage for some (especially if they lack fatty tissue) of preventing them injecting their insulin too far in, into the muscle instead of into the subcutaneous tissue. Besides being painful this causes the insulin to be absorbed much more quickly and hypoglycaemia can occur.

Short needles do not work for everybody. If you are overweight you may have too much fatty tissue under your skin so the short needle will deliver a too-shallow injection resulting in insulin leaking rather than being absorbed into the bloodstream.
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3. What thickness needle to use?

Needles come in different 'gauge's. The bigger the gauge number the thinner the needle is. Insulin needles come in gauges of 28, 29, 30 and 31.

For the differences see below:-
28 gauge .014 inches outside Diameter
29 gauge .013 inches outside Diameter
30 gauge .012 inches outside Diameter
31 gauge .012 inches outside Diameter
(though the last two may appear the same they actually have a differing wall thickness.)

You would imagine that the thinner the needle better but this is not always the case.

The actual wall thickness of the needle may be less and therefore it is weaker. If you have tough skin or don't get your injection exactly straight then the needle may bend.

New innovations are coming up all the time. For instance the Japanese Terumo Corporation, a medical equipment manufacturer, and Okano Industrial Corp., a small firm renowned for its metal-pressing technology, have co-operated to make the worlds thinnest needle, one that is just 0.008 inches (0.2 mm) in diameter and that claims to be virtually painless.

Called the Nanopass33 it won the Japan Industrial Design Promotion Organisation's Good Design Grand Prize.

It went on sale in July 2005 to hospitals and other medical facilities, under the brand name Microtaper Needle. A pack of 70 syringes is around $17.50.

I have not been able to find out which countries if any, this is available in at the moment. If you really want this needle try asking your doctor or pharmacist.



It appears than even now, in 2013, these are not available for us, as private individuals, to buy. Seems a great pity that they have restricted it to ‘big business’.

To read the interesting story behind this needle go to:-
The award-winning Nanopass 33 needle.

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4. Do you intend to reuse your syringe?

Though the syringes are supposed to be disposed of after one use, many people, due to financial constraints or a hatred of waste, do reuse them. If you intend to do this, and your doctor agrees, then here are some factors to consider:-

Sterility is very important. We are not insinuating here that all you readers do not have excellent personal hygiene. However you may have a wound on your hand (just a scratch can carry infection) or be ill with something other than diabetes at the time that decrees your resistance to infection. When this is the case it would be better not to reuse a syringe.

Be sure to pump the plunger up and down after injecting to get rid of any insulin that may be left in the needle.

Always take care to keep the needle clean. Some people suggest wiping it with an alcohol swab before replacing the cap while others feel that cleaning the needle with alcohol may remove the silicon coating that results in less painful injections. You can try both approaches and see what works for you.

The needle must always be recapped after each use. This is not quite as easy as it sounds, needing a certain amount of manual dexterity and good eyesight. A mistake can mean you stick the needle into your finger instead of the cap - ouch!

Keep the syringe in the fridge between uses.

Use a separate clean syringe to inject the air into your insulin vials. Keep this syringe for that purpose only and use another for drawing out the insulin. This will stop you blowing any old insulin that has crystallised within the needle back into the vial along with the air.

Do not continue to use a syringe once the markings start to rub off, you do not want to give an inaccurate dose.

Once the needle gets blunt, or worse, bent, which it does not only from going into you but even more from going into the rubber stopper of the insulin vial it is time to discard the syringe. Pain and bruising are not worth the minor savings!

The new ultra fine needles are more prone to bending, which is difficult to see. They can do so even on a single application, the tip forming a hook shape which, besides making it dashed painful can also break off under the skin, leaving a tiny bit behind - and you know how splinters hurt, never mind fester!
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Pre-filled syringes.

Syringes do not come this way but if you are someone with visual or neurological problems that makes filling your syringes difficult you can get someone else to fill a number of syringes for you. These can then be kept in the fridge for as long as 30 days. The needle should preferably be stored pointing upwards so that it does not become clogged with suspended insulin particles.

You can also store a number of premixed insulin syringes (mixture of two different insulins) but remember to roll them between the hands to mix the insulin before giving the injection.

If you think using pre-filled syringes will be of benefit discuss this with your doctor first.
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Who makes insulin syringes?

There are a large number of companies making the different brand name syringes plus others who make generic syringes. List below are some of them:-

1. BD (Becton, Dickinson and Company)
2. Turemo
3. Monoject
4. Ulti Med, Inc.
5. Aimsco
6. ReliOn
7. Abbott Laboratories
8. Can-am Care
9. Inviro Medical Devices Inc
10. Exel International
11. Allison Medical, Inc.
12. Medical Plastic Devices

Most make a whole range of syringes and you should find one to suit your needs. The generic are, as is always the case with generics, cheaper than the brand names but do not appear to lack anything in quality.

Ulti Med, Inc. make U40 syringes which can be hard to find but are used extensively for diabetic pets.

For a syringe reference guide go to Diabetes Health Magazine.

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Advantages of using a syringe.

With the advent of other forms of insulin delivery you might wonder why so many people still stick with the classic syringe. Here are a few of the possible reasons:-

1. Cost. Syringes are still the least expensive option. They are also frequently the device covered by insurance or medical plan, especially in the US.

2. Simplicity. They are easy to learn to use - after all very young children have been taught to inject themselves.

3. Choice. They come in such a variety that you can usually find one to suit you.

4. Availability. Wherever you are in the world you will probably be able to find somewhere that will sell you a syringe.

5. Reliability. There is not much that can go wrong in a syringe - it has very few moving parts!

6. Flexibility. They allow you to use one type of insulin or to combine 2 types of insulin within a single syringe if needed.
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Disadvantages of using a syringe.

1.Only as accurate as the patient using them. Dosage errors can occur easily, especially if you have problems seeing the graduations or lack fine motor skills.

2. Very 'hands on' and visible - there is no way of disguising that you are about to stick a sharp object into yourself, (or someone else). For the 'needle phobic' this can be a serious problem.

3. Require a certain amount of care with filling and delivery - you do not want to inject yourself with air!

4. Inconvenient to carry around if you travel about, or even to work or school - you have all these bits and pieces to take care of.

5. Conspicuous - they are pretty obvious things and can get you some funny looks if you are forced by circumstances to use them in a public place. You can see the thought "drug addict" crossing people's minds as they drag their protesting child out of the restroom.
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This is something you never think of until you have to give yourself daily injections. In many places you cannot just turf your needles out with the trash. There can be stringent regulations in place about the disposal of sharp objects like syringes and lancets.

If your health care professionals do not advise you on what to do then check with your trash removal company or your local health authority. You do not want to be fined or prosecuted because of ignorance.

Why is safe disposal important?

Needles on syringes can cause physical injury like cuts or puncture wounds.

Potentially fatal disease such as Hepatitis, HIV/ AIDS and tetanus can be passed on via the blood or body fluids on contaminated needles.

Casually discarded needles can land up in some very dangerous places, like children's playgrounds or on beaches.

There are various assorted systems for safe disposal available, which apply to you is dependent on where you live.

In some places you can take your own container full of sharps to your doctors rooms or pharmacy and they will dispose of them for you, sometimes for a fee, sometimes for nothing.

Likewise some pharmacies sell special containers for you to put your sharps in.

In others a mail system exists. A special container is provided, for a fee of course, and you can mail the full one to a place that disposes of it for you and get supplied with another empty one.

There are companies that produce 'at home' disposal devices that burn or melt the needle, making it safe for normal disposal.

Syringes and lancets are not recyclable so be careful your metal or plastic container is not put in the recycle bin by mistake.

Needle 'clippers' are available that snip off the needle from the syringe and store the needle safely within themselves. They can hold a large number of needles, sometimes as much as a two years supply. After that they still require to be properly disposed of. The needleless syringe can be tossed away with the normal trash.

Even if your area does not have any regulations it would be the action of a responsible person to place your sharp objects in a puncture resistant container such as a used coffee can or a strong heavy plastic container (bleach bottles are good), preferably with a small neck that can be tightly sealed, to prevent anyone who deals with the garbage getting inadvertently stuck.

Remember that in many third world countries (and these are the ones more likely to have no regulations in place) many adults and children comb the garbage heaps as their only form of livelihood and one does not wish to be responsible for causing them harm.

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(Checked and updated April 2013)