Diabetes is a worldwide public health challenge, with the number of adults diagnosed with diabetes now reaching 415 million worldwide.¹ In Ireland, an estimated 225,840 people are living with diabetes and that number is set to rise.² However, if treated and managed correctly, people with diabetes can lead very active and healthy lives.

It is well established that improving glycaemic control reduces the risk of people with diabetes developing long-term complications; the Diabetes Control and Complications Trial (DCCT) showed that keeping blood glucose levels as close to normal as possible slows the onset and progression of the eye, kidney, and nerve damage caused by type 1 diabetes³ while the UK Prospective Diabetes Study (UKPDS) showed conclusively that the complications of type 2 diabetes could be reduced by improving blood glucose control.⁴ In the longer-term, poor glycaemic control can increase the risk of complications including kidney failure, blindness and limb amputation, all of which have a devastating impact for the individual.⁵

Healthcare workers can help people with diabetes to achieve optimum glycaemic control (and thus avoid complications) through encouraging the active management of their condition. This includes having an effective exercise regime and a managed diet, making sure that glycaemic levels are optimally managed, but also, for patients using insulin injection therapy, having a good injection technique that leads to accurate insulin delivery.

Correct injection technique (IT) is crucial for injectable therapies like insulin to achieve optimal glycaemic control. A number of factors contribute to good IT including the injection process, needle length, and the rotation of injection sites.⁶

Informed healthcare workers can educate people with diabetes on correct injection technique, improving personal patient outcomes and encouraging on-going management of their condition.  The following case study of one patient shows the significant positive impact the injection technique and active condition management can have. 

Case study

This case study concerns a 32-year-old woman who has been living with type 1 diabetes for 16 years. Her last severe episode of hypoglycaemia was in 2007; she presented for preconceptual care in December 2014 following a miscarriage earlier that year.

Despite living with diabetes for 16 years, discussion revealed that her knowledge of self-care and condition management was outdated. She was using an 8mm needle and failing to rotate injection sites. She also routinely injected into areas of lipohypertrophy (a rubbery tissue growth under the skin⁷) and 50% of her glucose levels were above targets.

The patient was advised to follow best practice injection technique, including rotating injection sites, using a 5mm needle and avoiding injections into lipohypertrophy. In the six months following this advice, only 10% of her daily control glucose levels were above targets and her insulin usage dropped by 18 units from an original total daily dose of 76 units.

Following this intervention, the patient was in a better position to improve her glycaemic control for pregnancy; she achieved a pregnancy in 2015 and delivered a healthy baby girl in December 2015. 

Best practice injection technique

As this case study shows, a number of factors contribute to good injection technique and improved glycaemic control, including needle length and the rotation of injection sites.⁶ Informed healthcare workers can educate people with diabetes on correct injection technique, improving personal patient outcomes.

For reliable absorption, insulin should be injected into the subcutaneous fat layer. This allows it to be absorbed at a more predictable rate, which can lead to more stable glycaemic control.⁸ If insulin is injected intramuscularly it may be absorbed too quickly, leading to greater glycaemic variability and potentially an increased risk of hypoglycaemia.⁹ However, it makes no difference whether insulin is injected into deep or shallow subcutaneous tissue; it is absorbed at a similar rate.¹⁰

While subcutaneous depth can vary from person to person, skin thickness ranges from 1.2-3mm regardless of gender, age, BMI or ethnicity.¹¹ Short (4mm or 5mm) pen needles are appropriate for use for everyone carrying out insulin injection as they simplify injection technique (no need for a skin-fold in most cases) and will consistently pass through the skin to the subcutaneous layer and reliably deposit insulin with low risk of intramuscular injection (see Figure 1).¹²

 (click to enlarge)

It has been noted that insulin users sometimes skip their injection or restrict their number of daily injections.¹³ Since short needles in general seem to present a perceived less painful injection experience,⁹ they may also play a significant role in encouraging people with diabetes to adhere to their insulin injection regimen and improve their health outcomes.

Good injection technique should also include a correct method of site rotation, rotating both injection sites and within injection sites. Each injection site area (eg. abdomen, thighs or buttocks) should be used for up to one week maximum and those administering injections should move to the next injection area subsequently, always moving in the same direction, clockwise or anti-clockwise. Injection sites within any area should be spaced at least 1cm from the last injection to avoid repeat tissue trauma.¹⁴

It has been shown that correct injection site rotation appears to be the critical factor in preventing lipohypertrophy (see Figure 2). An appropriate regime which rotates injection sites can also help reduce the size of lipohypertrophic lesions, as the site begins to recover from repeated insulin injections. 

 (click to enlarge)

Lipohypertrophy can cause complications of its own; diabetes patients who inject into areas of lipohypertrophy can experience delayed and erratic absorption of insulin, potentially leading to increased occurrence of complications such as hypoglycaemia and glycaemic variation.^15,16

Conclusion

Good injection technique is a crucial aspect of improving condition management for people with diabetes, allowing them to live normal and healthy lives. Educational follow-up regarding injection technique is incredibly important as although knowledge may have been imparted at an initial consultation, it is often not until a later stage that problems related to poor injection technique (such as lipohypertrophy) arise. 

Best practice technique may also have been updated. It is therefore important to re-visit injection technique and examine injection sites as part of routine, ongoing management of an injectable therapy to achieve its optimal effect. Healthcare workers that come into contact with people with diabetes have a duty to thoroughly check an individual’s injection technique, sites and re-educate where applicable.

For further information and guidance on best practice injection technique visit www.fit4diabetes.com

References

1. IDF Diabetes Atlas, 7th edition, 2015
2. http://www.diabetesatlas.org/   
3. https://www.diabetes.ie/about-us/diabetes-in-ireland 
4. National Diabetes Information Clearinghouse, DCCT and EDIC: The Diabetes Control and Complications Trial and Follow-up Study, https://www.niddk.nih.gov/about-niddk/research-areas/diabetes/dcct-edic-diabetes-control-complications-trial-follow-up-study/Documents/DCCT-EDIC_508.pdf
5. UKPDS, https://www.dtu.ox.ac.uk/ukpds/ 
6. Torpy, Janet M; Lynm, Cassio; Glass, Richard M.  Diabetes.  Journal of the American Medical Association. 301, 15, (2009): 1620. http://jama.jamanetwork.com/article.aspx?articleid=183754
7. Grassi G, Scuntero P, Trepiccioni R, Marubbi F, Strauss K, Optimizing Insulin Injection Technique and its Effect on Blood Glucose Control, Journal of Clinical & Translational Endocrinology (2014), doi: 10.1016/j.jcte.2014.07.006
8. Blanco M, Hernández MT, Strauss KW, Amaya M. Prevalence and risk factors of lipohypertrophy in insulin- injecting patients with diabetes, Diabetes and Metabolism, 2013; 39(5):445-53
9. Frid A, Fat thickness and insulin administration, what do we know? Infusystems  Int. 2006;5(3):17-19.
10. Birkebaek NH, Solvig J, Hansen B, Jorgensen C, Smedegaard J, Christiansen JS. A 4-mm needle reduces the risk of intramuscular injections without increasing backflow to skin surface in lean diabetic children and adults. Diabetic Care, 2008; 31(9):e65
11. Frid et al (1992) Intraregional Differences in the Absorption of Unmodified Insulin from the Abdominal Wall. Diabetic Medicine 1992; 9: 236-239
12. Gibney MA, Arce CH, Byron KJ, Hirsch LJ. Skin and subcutaneous adipose layer thickness in adults with diabetes at sites used for insulin injections: implications for needle length recommendations, Current Medical Research & Opinion, 2010; 26(6):1519-1530
13. Hirsch LJ, et al. Glycemic control, reported pain and leakage with a 4mmx32G pen needle in obese and non-obsese adults with diabetes: a post hoc analysis, Current Medical Research & Opinion, 2012; 28 (8): 1-7
14. Peyrot M, Rubin R, Lauritzen T et al. Resistance to insulin therapy among patients and providers: results of the cross-national Diabetes Attitudes, Wishes and Needs (DAWN) study. Diabetes Care, 2005; 28: 2673 2679
15. Thatcher G. Injectable therapy injections. The case against random rotation. American Journal of Nursing 1985; 85:690-692
16. Famulla S, et al. Lipohypertrophy Leads to Blunted, More Variable Insulin Absorption and Action in Patients with Type 1 Diabetes. Diabetes. 2015; 64 (S1)
17. Hövelmann U, et al. Insulin Injection into Regions with Lipohypertrophy (lipo) Worsens Postprandial (PP) Blood Glucose (BG) Versus Injections into Normal Adipose Tissue (NAT). 2015; 64 (suppl1). Poster presented at ADA meeting, Boston, MA. June 2015