Cloudy insulin must be properly re-suspended before use or the strength of the insulin delivered can vary dramatically and the expected impact will not be achieved. This may result in hypoglycaemia or hyperglycaemia (Gin and Hanaire-Broutin, 2005).
Re-suspension is achieved by rolling the vial or cartridge 10 times then gently inverting it 10 times and visually checking that it is a milky white colour before it is injected.
Lifted skin fold technique
If a needle longer than 8mm is used (in adults), a lifted skin fold must be used to avoid the risk of injecting insulin into muscle (Hicks et al, 2011; Gibney et al, 2010).
The technique used for this is another area of concern. While making a lifted skin fold reduces the chance of intramuscular injection, releasing the skin fold too soon, lifting it incorrectly or using the whole hand to lift it increases this risk.
The best method is to lift the skin between thumb and two fingers with one hand, pulling the skin and fat away from the underlying muscle, and holding until the insulin has been injected (Figs 1a and 1b).
A lifted skin fold should be used with a needle length less than 8mm in patients who are very thin and in children (Hicks et al 2011).