An insulin syringe is a syringe with a small needle made specifically for self-administration of insulin in diabetic patients. The syringe is designed to inject the medication into the subcutaneous tissue. This is the desired area for injection of insulin because the fat cells allow medications to be absorbed constantly and slowly, for a longer lasting effect.
An insulin syringe typically has a barrel, plunger, and needle. The barrel is the hollow chamber that holds the insulin. Markings on the barrel are provided for measurement in International Units, the standard unit of measure for insulin.
Most insulin syringes have 100 unit barrels. A lo-dose insulin syringe may have a 50 unit barrel. In most cases, insulin is provided in U-100, meaning that 100 units of insulin are contained in one milliliter of fluid.
The plunger is the part of the syringe that is pulled back to draw liquid into the barrel, and compressed to push the liquid out of the barrel. It fits tightly within the barrel, and has a rubber tip on one end and a plastic disc on the other. Pushing the disc on the plunger causes the rubber tip to push the insulin out of the barrel and through the needle.
The needle on an insulin syringe is very thin and short for injection into the subcutaneous tissue. Subcutaneous tissue is the fatty layer of tissue located under the skin. The pain associated with subcutaneous injections is usually minimal.
Patients should always wash their hands before preparing and administering an insulin injection. This will minimize exposure to bacteria through the injection site. Using an alcohol wipe to cleanse the top of the insulin bottle will also help to ensure cleanliness.
When preparing an injection, the patient will likely inject air into the insulin bottle, equal to the amount of medication that will be needed. The patient will then turn the bottle over so that it is upside down, and pull back on the plunger to draw the appropriate amount of insulin into the syringe. Flicking the barrel will cause any air bubbles to rise to the surface.
By pressing the plunger, the patient removes any air from the barrel and may check for an accurate dosage. After removing the needle from the bottle, an injection site may be chosen.
Injection sites are usually located on the upper arm, thigh, or abdomen. The area should be cleansed with an alcohol wipe in a circular motion, from inside to outside of the chosen area. Holding the syringe like a dart in one hand, the patient can firmly pinch the skin with the other hand, and quickly insert the needle at a 90° angle. Slowly pressing the plunger will inject the medication.
An alternative to an insulin syringe is an insulin pen. These pens usually come with a pre-filled insulin cartridge that features a dial to determine the dose. Durable insulin pens are reusable and use replaceable insulin cartridges, while pre-filled pens are disposable and can be discarded when the insulin cartridge is empty.
Insulin syringe and pen needles should be disposed of properly. For safety purposes, used needles should be discarded in an appropriately-labeled, sharp medical waste container. These hard-sided containers resist punctures, so that no one can be injured by contact with a used needle.