Needle reuse can cause increased pain and tissue damage at the point of
injection. It can also directly impact the accuracy of the dosage of
insulin and therefore affect your glycaemic control.
Injection pain
To make injections virtually painless, insulin needles are finely ground and lubricated. Repeated use leads to tip damage and loss of lubricant which increases pain and discomfort during the injection.
Microtrauma
Reuse can bend the needle tip into the shape of a hook. When removing the reused needle after injection, the hook lacerates tissue, causing microtrauma.
There is increasing evidence that this microtrauma is involved in the formation of lumpy nodules also known as "lipodystrophy".
Needle bending and breakage
Reuse of needles can result in microscopic bending and breakage of the tip. This initial microscopic tip damage can result in increased force to puncture the skin and lead to accidental bending of the needle as a whole.
The micro- and macroscopic damage are both implicated in the complete breakage of needle.
Needle clogging
Insulin remaining in the needle between injections may crystallise and create a blockage, making it impossible to deliver the insulin during the next injection.
Dosage accuracy
Keeping a needle on your insulin pen between injections leaves an open passage to the insulin, allowing insulin to leak out of the cartridge and/or air to be drawn into the cartridge.
Insulin leakage
Mixed insulin (e.g. 30/70) contains two types of insulin (regular/rapid acting insulin and intermediate acting insulin). The regular insulin is more fluid and leaks more readily from the open passage created by leaving the needle attached. This leakage changes the relative concentration of the insulin mixture.
Injecting the incorrect mixture will negatively impact your glycaemic control.
Air entry
The air bubbles that enter into the cartridge through the open passage lengthen the time required to inject the whole of your insulin dose.
If you do not correspondingly lengthen your injection time, you will not receive your full dose of insulin which will negatively impact your glycaemic control.
Sterility
Single use products are guaranted sterile for one use only. If you intend to reuse a needle, you should be aware that it is no longer sterile.
