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Pointy Tips on Needles

By Carolien Koreneff, CDE-RN, FADEA

People with diabetes often end up having to use needles regularly. Whether they are lancets for finger pricking, pen needles for insulin injections or introducer needles for continuous glucose monitoring (CGM) sensors or insulin pump cannulas, they become a part of everyday life with diabetes. In this article Carolien Koreneff, an experienced registered nurse and credentialled diabetes educator, provides us with tips that will help to minimise any discomfort associated with injections.

 

Size matters

It was once believed that certain people would need longer needles when injecting diabetes medications such as insulin because of a thicker skin, but research has found that this is not the case. Irrespective of a person’s body mass index (BMI) or race, skin thickness does not change all that much – most adults have a skin thickness of 1.9-2.4mm1,2,3.

What changes when one becomes overweight or obese is the fat layer underneath the skin, the subcutaneous tissue. This means that a person of any gender, age or weight can safely use a short 4 or 5mm pen needle for the injection of diabetes medications2.

It has been estimated, that a 4mm pen needle, injected at a 90-degree angle will get insulin into the subcutaneous tissue 99.5% of the time2,3.

Longer pen needles, above 6mm in length, can go too deep and can result in injecting the medication into a muscle. Intramuscular injections can increase the speed at which medication is absorbed and this can increase the risk of hypoglycaemia (low blood glucose levels), make blood glucose levels less reliable and is a lot more painful3.

It is especially important to use short pen needles for children and slimmer people as their risk of accidental intra-muscular injections is increased3.

An 8mm pen needle is 38 times more likely to end up in a muscle than a 4mm pen needle2. If the patient insists on using longer pen needles, above 6mm in length, it is recommended to use a skin fold4. Watch our Injection Technique Best Practice webinar to get clear on the right technique.

 

Location, location, location

The recommended sites for injections sites are the abdomen, thighs and buttocks3,4. When injecting into the abdomen we should observe the following boundaries:

  • At least 1cm above the pubic bones
  • At least 1cm below the lowest rib
  • At least 1cm away from your navel and
  • On the sides, at the flanks (between the ribs and the hip)

Injecting into the arms or legs increases the risk of injecting intramuscularly and can speed up insulin action when the person exercises and therefore is not recommended.  The increased use of the muscles during physical activity can increase glucose absorption due to improved insulin sensitivity, and this can increase the risk of hypoglycaemia3.

An injection site should not be used more than once every 4 weeks.

 

Once, twice, sixteen times… what is the limit?

Needles start to become blunt after just one use, it is Best Practice to use a new needle for every injection9.

needle use

Photograph from https://www.bluegrassdoctorspt.com/apps/blog/show/44468568-do-not-reuse-needles-

The image above highlights what happens to the needle, and in particular the needle tip, when a needle is re-used.

Blunt needles cause increased pain when injecting, as well as more bruising and bleeding. There is also an increased risk of skin trauma and infection, as after the first use the needle is no longer lubricated or sterile.

Injecting through clothing blunts needles more and can increase the risk of insulin not being injected into the subcutaneous tissue, particularly if the item of clothing is thick, like jeans, and so, injecting through clothes is not recommended9.

Around 70% of people who reuse pen needles are found to have lipohypertrophy which can increase insulin variability and lead to erratic blood glucose levels.

 

Lipohypertrophy

Lipohypertrophy, sometimes called a lipo for short, is a thickened “rubbery” swelling of tissue that is sometimes soft and sometimes firm5. The fatty lumps below the skin grow larger over time. Lipohypertrophy causes glucose variability and increases the risk of hypoglycaemia3,6,7.

Although most often you see a raised area, it isn’t always easy to see areas of lipohypertrophy. In many cases it may be easier to feel it.

Lipohypertrophy is the most common complication of insulin treatment and is more common in those with type 1 diabetes than in people with type 2 diabetes. For starters due to the fact that people with type 1 diabetes tend to have a higher number of daily injections but also because people with type 1 diabetes are often injecting for many more years.

There are several factors at play in the development of lipohypertrophy6,8:

  • Recurrent injections into the same area
    • Due to repeated trauma to the site, when you do not rotate your injection sites
  • The repeated use of the same needle
    • Due to damage to the needle and due to the loss of the lubricant that helps the needle slide through the skin easier
  • The use of long (>6mm) pen needles
    • As longer needles cause more discomfort the person may start favouring spots where the discomfort is less, which will lead to overuse of the area
  • The insulin itself
    • due to its strong growth-promoting properties

Research has shown that injecting into a lipo can affect blood glucose levels. It was found that 39% of people with lipohypertrophy have unexplained hypoglycaemia5.

On average, a person with a lipo can require around 10 units of insulin more every day, compared to people without, as the insulin does not get absorbed as well. This increased need for insulin can lead to weight gain, which can cause or increase insulin resistance. Interestingly, people with insulin resistance tend to require larger amounts of insulin and as a result can gain further weight and are at increased risk of hypoglycaemia.

If the person switches injections from an area of lipohypertrophy to normal healthy tissue, often a decrease in the insulin dosage is required, because the full dose of insulin will be absorbed5. The amount of change varies from one individual to another and should be guided by frequent blood glucose monitoring.

Research has also shown that 99% of those with lipohypertrophy do not rotate their injection sites or don’t rotate correctly5.

 

Site rotation

Patients should rotate their injection sites, as not doing this (correctly) and injecting into the same site repeatedly causes lipos to develop.

It is important to move injections at least half an inch (around 1cm or approximately the width of an adult finger) away from the previous injection and to systematically rotate the sites1.

Dividing the injection area into quadrants, using 1 quadrant per week and rotating quadrant to quadrant in a consistent direction, such as clockwise has been proven to reduce the risk of lipohypertrophy and glucose variability.  An injection site rotation grid can also be helpful.

site rotation injections

Reducing painful injections

If patients find the injections painful you can recommend the following3:

  • Injecting insulin at room temperature rather than when cold.
  • If using alcohol to clean the skin (although this is generally not necessary), injecting only after this has dried.
  • Using a new needle for each injection.
  • Using needles of shorter length and smaller diameter.
  • Penetrating the skin quickly with the needle.
  • Injecting the insulin slowly.
  • Not changing the direction of the needle during insertion and withdrawal.

Bruising

Some people develop bruising at the injection site, this can happen if they are too rough and push the needle in too deep. There is no need to have the skin buckle under the pressure of the needle.

 

Some other important factors

Cloudy insulin must be resuspended before each injection to reduce the risk of hypoglycaemia and glucose variability. The recommended method is gentle mixing by tipping (rocking) and rolling the insulin 10-20 times until the mixture is even in colour without any visible particles. The preparation should not be shaken vigorously because it can affect the kinetics of the preparation.

Volume of medicine – Insulin absorption is slower with larger doses of insulin and there may be more discomfort and leaking. There is currently no consensus amongst healthcare professionals regarding the largest volume of medicine that can be injected subcutaneously in a single injection. However, for doses over 50 units it is recommended to divide it into 2 injections of smaller doses.

Leakage – Leakage is more related to dose volume and not needle length. If the needle is withdrawn too soon leakage is more likely to occur; this can be avoided by increasing the time the needle is left in place after the injection.

Air shot – it is recommended to expel 1-2 units of insulin before dialling up the dosage. Some people try and take a short cut by dialling up a couple of extra units and squirting a bit out before inserting the needle, but this is dangerous as they will squirt out slightly different amounts each time and this could cause dose variability which can affect blood glucose levels.

Preparation of injection site – If the site requires cleaning, soap and water is enough. Alcohol swabs are usually not needed in the home environment and may toughen the skin.

Disposal of sharps – Syringes, pen needles, lancet (finger prickers) and insertion needles for CGM or pump infusion sets are considered community sharps and should be disposed of in a puncture-resistant plastic container. Full sharps containers can be disposed of at the local hospital, participating pharmacies or at a local community sharps disposal. Do not dispose of sharps in rubbish bins.

 

References:

  1. Frid AH, Kreugel G, Grassi G et al. Mayo Clin Proc. September 2016:91(9):1232-1233.
  2. Gibney M, Arce C, Byron K, Hirsch L. Curr Med Res Opin. 2010; 26(6): 1519-1530.
  3. Australian Diabetes Educators Association (ADEA). Clinical Guiding Principles for Subcutaneous Injection Technique, December 2019.
  4. Frid AH, Kreugel G, Grassi G et al. Mayo Clin Proc. September 2016:91(9):1231-1255
  5. Blanco M, Hernandez M, Strauss K, Amaya M et al. Diabetes Metab. 2013; 39(5): 445-53.
  6. Frid AH, Hirsch LJ, Menchior AR et al. Mayo Clin Proc. September 2016:91(9):1224-1230.
  7. Vaag A, Damgaard Pedersen K, Lauritzen M, Hildebrandt P, Beck-Nielsen H. Diabetic Medicine 1990; 7: 335-342.
  8. Look D, Strauss K. Diabetes J. 1998; 10:31-34.
  9. Fleming Dr, Jacober Sj, Vandenberg Ma, Et AL. The safety of injecting insulin through clothing. Diabetes Care 1997 Mar; 20: 244–7.

 

 

Injection Technique Best Practice

https://www.adea.com.au/wp-content/uploads/2015/11/Injection-Technique-Final-digital-version2.pdf