Insulin is delivered through a subcutaneous injection (in the fatty layer between the skin and the muscle).
This can be delivered through an insulin pen, a syringe or through an insulin pump.
The needles supplied on NDSS are used for injection from an insulin pen.
A diabetes educator can help you select the correct needle length, specific to their situation.
All needles and syringes should be used once, then discarded in a dedicated sharps disposal container.