Diabetes UK is aware that there is debate as to the suitability of using the arms as an injection site. This is based on the assumption that it is difficult to inject subcutaneously in this area, due to the relatively thin layer of subcutaneous adipose tissue, leading to a high number of intramuscular injections.
Intramuscular injections have been associated with a higher risk of hypoglycaemia (1) and the potential for less stable control.
This problem may be avoided in other injection sites by the ‘pinch up’ technique, with the injection given at a 45 degree angle, if the person has little subcutaneous adipose tissue.
While this is virtually impossible for an individual to achieve without assistance if injecting into the arm, the development of shorter length needles, means that this problem can be reduced.
Research into the depth of adipose tissue in the arms in adults suggests that the average thickness is 9mm in men and 15mm in women (2). This would suggest that for the average adult, injecting into the arms with an 8mm needle would be successful. Lean adults would need to consider using a shorter needle or avoiding the arms. However, another study estimates that injection site subcutaneous tissue depths are considerably less - for men 5.8mm (+/- 1.5) and for women 10.1mm (+/- 2.4) (3). This would suggest that for men, considerably shorter needles would be required.
Evidence form Becton Dickenson suggests that the use of 5mm needles in adults should not be a matter of concern, if used without a pinch up unless the individual is very thin (4), and indeed should be the needle of choice for injecting in the arm (5).
Children
Several studies have indicated that using 8mm, rather than 12.7 mm needles, can lead to an improved rate of subcutaneous injections in children with Type 1 diabetes (6) even when injecting into the arms. However, this certainly does not eradicate the problem as only 45.5 per cent of children, injecting into the arm with an 8mm needle, successfully injected subcutaneously rather than intramuscularly (6). There is a presumption that using the shorter needles, now available, that the arms could be used more successfully. However, a further study which focused on injecting into the anterior thigh and abdomen suggests that even an angled 8mm or perpendicular 6mm injection did not prevent I.M. injection (7). It can therefore be assumed that the chance of I.M. injection when using the arm would be even greater, due to the relatively thin layer of adipose tissue. This study included children between the ages of 6-14, and it is recognised that there will be significant differences in the depth of adipose tissue in the arms within this age range.
Evidence from Becton Dickenson suggests that children prefer using 5mm needles and had less pain and hypoglycaemia when using 5mm needles rather than 8mm needles (4).
In conclusion, Diabetes UK would suggest that the arms may be used as a site for injection in both adults and children provided the appropriate length of needle, and the correct technique for administration of insulin, is used. This should be individually assessed by the diabetes team. However, extreme care should be taken in children under the age of 6.
People using their arms should be encouraged to monitor their blood glucose control more regularly, to ensure that their technique is delivering the insulin appropriately.
They should also be warned of the risk of hypoglycaemia following injection into the arm. Parents should be encouraged to use the ‘pinch up’ technique if using the arms as a site for their children and should use shorter needles.
References
- Vaag, A. et al. Intramuscular versus subcutaneous injection of unmodified insulin: consequences for blood glucose control in patients with Type 1 diabetes mellitus. Diabetic Medicine 7:335-342, 1990.
- Frid, A., Linden, B. Where do lean diabetics inject their insulin? A study using computed tomography. British Medical Journal 292:1638 1986
- Throw J.C., Coulthard A. and Home P.D. Insulin injection site tissue depths and localization of a simulated insulin bolus using a novel air contrast ultrasongraphic technique in insulin treated diabetic subjects. Diabetic Medicine 9 (10): 915-920 1992.
- Strauss K. Guidelines for Using Ultra-short (5mm) Insulin Needles. Becton Dickenson.
- Strauss K Insulin Injections in the Arms or Thighs: Do these sites need specific recommendations? Becton Dickenson
- Tubiana-Rufi, N. et al. Short needles (8mm) reduce the risk of intramuscular injections in children with Type 1 diabetes. Diabetes Care 22:10, 1999.
- Hoffman P.L. et. al. An angled insertion technique using 6mm needles markedly reduces the risk of intramuscular injections in children and adolescents. Diabetic Medicine 24 (12): 1400-1405 2007.
February 2009