Insulin

Administration of insulin

Injection technique

• Injections by syringe are usually given into the deep SC tissue through a two-finger pinch of skin at a 45–90° angle
• The pinch of skin is used to avoid the risk of administering insulin IM
• The SC fat layer should be thicker than the needle length. Very short needle lengths (e.g. 5 or 8 mm) are now available in some countries and they are particularly useful for young, slim children
• All suspensions of insulin (e.g. NPH, IZS, pre-mixes) must be resuspended before injection by rolling or inverting the vial or pen injector device (10 times) so that the cloudy suspension mixes thoroughly and uniformly
• Pen injector technique requires careful education including the need to ensure that no airlock or blockage forms in the needle; a wait of 5–10 seconds after pushing in the plunger helps to ensure complete expulsion of insulin through the needle

Self-injection

• It should be emphasized that a proportion of people with diabetes have a severe and long-lasting dislike of injections, which may influence their glycemic control
• There is great individual variation in the appropriate age for children to self-inject
• The appropriate age relates to developmental maturity rather than chronological age
• Most children over the age of 10 years either administer their own injections or help with them
• Younger children sharing injection responsibility with a parent or other care provider may help to prepare the device or help push the plunger and subsequently under supervision be able to perform the whole task successfully
• Self-injection is sometimes triggered by an external event such as overnight stay with a friend, a school excursion or diabetes camp
• Parents or care providers should not expect that self-injection will automatically continue and should accept phases of non-injection and the need to provide help
• Younger children on multiple injection regimens may need help to inject sites that are difficult to reach (e.g. buttocks) to avoid lipohypertrophy

Regular checking of injection sites, injection techniques and skills remains the responsibility of parents, care providers and health professionals

Self-mixing of insulin

• There is no uniformity of advice but most often it is taught that clear insulin (short-acting) is drawn up into the syringe before cloudy insulin (intermediate- or long-acting)
• If the cloudy insulin is lente type, the mixture must be administered immediately otherwise the short-acting component interacts
• Insulins from different manufacturers should be used together with caution as there may be interaction between the buffering agents
• NPH and lente insulins should never be mixed
• Rapid-acting insulin analogs may be mixed in the same syringe as NPH or lente

Devices for insulin delivery

Insulin syringes

• Plastic fixed-needle syringes with small dead space are preferable to glass syringes
• Syringes are available in a variety of sizes in different countries and should enable accurate dose delivery, but it is desirable for small dose, 1 unit per mark syringes (e.g. 0.3 ml) to be available for small children
• Plastic fixed-needle syringes are designed for single use (but many children and adolescents successfully re-use them without a significant increase in risk of infection). Re-use should be discouraged if there is concern about hygiene

• Insulin syringes must have a measuring scale consistent with the insulin concentration (e.g. U 100 syringes)
• Syringes must never be shared with another person because of the risk of acquiring blood-borne infection (e.g. hepatitis, HIV)
• It is advisable that all children and adolescents with diabetes should know how to administer insulin by syringe because other injection devices may malfunction

Disposal of syringes

• Appropriate disposal procedures are mandatory

• Specifically designed and labeled ‘sharps containers’ may be available from pharmacies and diabetes centers
• Special needle clippers (e.g. Safeclip®) may be available to remove the needle and make it unusable
• Without a sharps container, syringes with the needles removed may be stored and discarded in opaque plastic containers or tins for garbage collection

Subcutaneous indwelling catheters

• Such catheters (e.g. Insuflon®) inserted using topical local anesthetic cream may be useful to overcome problems with painful injections
• These catheters are used in some centers for introduction of multiple injection therapy

Pen injector devices

• Pen injector devices containing insulin in prefilled cartridges have been designed to make injections easier and more flexible. They eliminate the need for drawing up from an insulin vial, the dose is dialled up on a digital scale and they may be particularly useful for insulin administration away from home, at school or on holiday
• Special pen injection needles of small size are available and may cause less discomfort on injection
• Pen injectors of various sizes and types are available from the pharmaceutical companies. Availability is a problem in some countries and although pen injectors may improve convenience and flexibility they are a more expensive method of administering insulin
• Pen injector devices are useful in children on multiple injection regimens or fixed mixtures of insulin but are less acceptable when free mixing of insulins is used

Automatic injection devices

• Automatic injection devices are useful for children who have a fear of needles. Usually a loaded syringe is placed within the device, locked into place and inserted automatically into the skin by a spring-loaded system
• The benefits of these devices are that the needle is hidden from view and inserted rapidly through the skin
• Automatic injection devices for specific insulin pen injectors are now available

Jet injectors

• High pressure jet injection of insulin into the skin has been designed to avoid the use of needle injection
• Jet injectors may have a role in cases of needle phobia
• Problems with jet injectors have included a variable depth of penetration, bruising, variable absorption of insulin, and cost

Subcutaneous insulin infusion pumps

• The use of external pumps is increasing and is proving successful even in young infants for stabilizing difficult diabetes
• Insulin pump treatment may be hazardous when education and adherence to therapy is inadequate because of the smaller depot of SC insulin and the risk of ketoacidosis
• Only short-acting or rapid-acting insulin analogs are used in the pumps