Administration of insulin by injection

Injections have been used in health care since the 1860s1. For those with diabetes insulin injections, for many years, necessitated the use of cumbersome glass and metal syringes. These were largely replaced in the 1970s by disposable plastic syringes, but it was not until the 1980s that innovative ‘pen’ devices were introduced, heralding a new era in insulin administrations. Subsequent years were to reveal the rising popularity of pen injectors, which now come in a variety of presentations, including both reusable and disposable devices, thus widening the choice for the individual with diabetes. However, as disposable insulin syringes still continue to be the choice of some clients, the importance of ensuring that they have a truly informed choice must be a priority with diabetes health professionals, necessitating that they themselves are regularly updated as to current available insulin devices. 1.0 ml (100 units) size/needle size 12.7 mm. Useful for injections of >50 units. Larger markings – easier to see. Units marked in twos. 0.5 ml (50 units) size/needle sizes 12.7 mm, 8 mm. Useful for injections <50 units. Marked in single units. Facilitates alterations of 1 unit. 3 ml (30 units) size/needle size 12.7 mm, 8 mm. Small syringe – useful for children. useful for injections <30 units. Facilitates alterations of <1 unit. Free on prescription. Disposable after use. Lightweight. Insulin can be ‘seen to be injected’. Attached needle in variety of sizes. Suitable for dosages up to 100 units. Less socially acceptable if injecting in public. Drawing up can be ‘fiddly’. Necessitates carrying a bottle and syringe. Requires adequate visual acuity (to see graded markings). Requires reasonable manual dexterity. Air can be inadvertently drawn into syringe. Currently available injector devices can be seen in the centre page. Most pens are free on prescription. Pen needles are free on prescription. Portable. Socially acceptable if injecting in public. Visible dial simplifies dosages. Audible ‘click’ with each unit overcomes many visual problems. Choice of needle sizes (12.7 mm/8 mm/6 mm/5 mm). Loading/unloading cartridges and attaching needles requires a degree of manual dexterity. Pen is heavier and larger than syringe. Length of pen means that movement during injection can cause bruising. Those with arthritis may find injector button difficult to press. injection depth injection sites injection technique. For everyday use, subcutaneous injection of insulin is preferred. As the body supply to the adipose layer is relatively poor compared with that to the intramuscular site, this will cause a delayed systemic absorption of insulin. As insulin is required to have an effect over several hours this makes the subcutaneous route ideal for insulin injections. there are dramatic differences in the distribution of subcutaneous tissue within different age groups and between men and women,4 as patients show variable stoutness and body mass distribution it is important to evaluate the sites suitable for a subcutaneous injection,5 appropriate needle length selection can help ensure a subcutaneous injection (3,4) and the risks of incorrect injection depth include intramuscular – accelerated absorption of insulin provoking erratic control or hypoglycaemia, bleeding intradermal – insulin leakage, lumps at injection sites immediately after injection, pain or localised immune response. Key injection areas shown in Figure 1. Each site has its own pattern of insulin absorption according to the type of insulin and the frequency and timing of injection. Injection sites Organise a rotation of injection sites. Inject into the same site at the same injection time. Do not mix areas and times to ensure a reliable absorption. Alternate left- and right-hand sides from one week to another. Chose the appropriate area according to the type on insulin. Refrain from injecting through clothing. Rotate injections sites within the same area in order to relevant the development of lipohypertrophy (lumpy nodules). Inject according to the appropriate technique, choosing the appropriate sized needle. By assessing the individual's injection areas, body mass distribution and using our knowledge of insulin kinetics we can then recommend an appropriate injection technique. Pinching up the skin is recommended when insulin injection is given at 90°. A correct pinch-up should be performed with the thumb and index/middle finger (Figure 2). Injection technique pinching up or not inserting at 45° or 90° choosing the right needle size: 5 mm, 6 mm, 8 mm, 12 mm, 12.7 mm. Needle manufacturers recommend that needles are designed for single use only (however, reuse of needles is a common practice). To avoid insulin leakage leave the needle in the skin for 5–10 seconds after injection, releasing the pinch-up when the needle is withdrawn. Inject 20–40 minutes before meals. Choose an appropriate area according to the time of day and type of insulin. Inject on clean skin with clean hands. Space out injections within each area, moving one finger breadth from the last site. Inject with the correct technique and needle size. use/storage of insulin cartridges preparation/use of pen devices use of disposable pen needles. Sample guidelines are detailed below, as presently in use within a large NHS hospital trust (Wilbourne, unpublished). These guidelines will be reviewed annually in January of each year. For advice or comments on the content of these guidelines contact JUDY WILBOURNE, Diabetes Nurse Specialist, Newcastle General Hospital, UK. Bleep 1593.