Insulin: Best Practices, Tips & Tricks

Insulin injections are used to treat both type 1 and type 2 diabetes. People use prescribed insulin in two forms:  a vial and syringe or pen.
This article will teach you how to use an insulin pen and/or a vial or insulin for insulin injection and give you tips and tricks on how to do it safely and effectively.


Needles for Insulin Injection

Standard injection needles come attached to a disposable syringe. Pen needles are separate disposable needles that are screwed onto a pen device. These needles are usually very fine. Insulin tips and how to use
The thickness of a needle is called its gauge. The smaller the gauge number, the thicker the needle; the larger the gauge number, the thinner the needle. For example, a 31-gauge needle is thinner than a 28-gauge needle.

Needles come in the following lengths:

  • The longest length is 1/2 inch (12.7 mm).
  • A “short” needle is 5/16 of an inch (8 mm).
  • A “mini” needle is 3/16 of an inch (5 mm).
  • The smallest needle is a “nano” needle (4mm).

Extremely thin people may need to angle the needle more in order to avoid injecting into the muscle, which can be very painful.
Never shake a vial or insulin pen. Never inject into a vein, as this is very dangerous. Sometimes the needle will strike a capillary in the fat layer. A small blood drop may be seen on the skin just after the injection or bruising may appear later. This is common and nothing to worry about. This does not mean that the medicine went directly into the vein.
It may, however, indicate a problem with the injection technique or the need for a shorter needle length.


Safe Injection Technique

Inspect insulin before injection. Clear insulin should have no floaters, discoloration or cloudiness.  Cloudy insulin should have no clumping or discoloration.
Choose an area of fat on the body with at least ½’-1” of pinchable thickness. Avoid injecting into muscle in areas where there is too little fat, such as the deltoid or top of the thigh (common in men).
Insulin tips and how to useSome insulin types absorb at different areas depending on the injection location.  The absorption rate is the same in all locations for newer analog insulins (Humalog, Admelog, Novolog, Apidra, Fiasp, Lyumjev, Lantus, Levemir, Basaglar, Toujeo and Tresiba).
Absorption rate differs for older, non-analog insulins (Regular, NPH and mixed insulin).
Note: For these insulins, the abdomen is the fastest, while the upper arms, thighs and buttocks are the slowest.
Using the same general area will result in more absorption consistency but can easily lead to tissue damage due to lack of site rotation. This should only be advised if there is a lack of other injection site options.
Rotate injections so as not to cause damage, lumps or scar tissue. Improper injection site rotation is likely to reduce absorption greatly over time and is often not correctable.

Additional tips:

  • Wash hands and clean the injection site every time.
  • Thoroughly “mix” vials or pens of cloudy Neutral Protamine Hagedorn (NPH) insulin prior to preparing the injection dose by slowly inverting or rolling the insulin container between the hands 5 times or 10 seconds.
  • Never reuse needles. Using the same needle repeatedly can clog the needle with crystalized insulin and dull the needle.  Dull needles increase tissue damage and promote scarring.
  • Never mix long-acting insulin detemir or glargine with another type of insulin in the same syringe. When taking detemir or glargine, don’t use a syringe that was previously used for another type of insulin.
  • Drawing insulin from an insulin pen or insulin cartridge renders the device inaccurate and unsafe for subsequent insulin delivery. Discard the pen or cartridge if insulin is removed by syringe.  Do not use an insulin pen or cartridge for injection once insulin has been withdrawn by syringe.

Injection Site Rotation

Poor site rotation reduces insulin absorption over time. The reduction in absorption can become significant, regardless of the type of insulin given.  The more injections per day, the more important it is to change the injection spot each time. Insulin tips and how to use
Consider a patient on a typical multiple daily injection regimen of 4 injections per day.
4 injections x 365 days = 1,460 injection per year.
Some patients may use an area for 5-10 yrs before receiving proper, specific site rotation instruction. 1,460 x 10 years = 14,600 small scars in the limited body area results in reduced medication absorption from gradually scarring of tissue –– whether lumps or indentations are visible, palpable, or not.
Try this: Inject 1-2” from the previous site in a sequential pattern until all sites within the fat pad area have been used. Stop using the area. Begin injecting in another subcutaneous fat pad region in a sequential pattern.


Insulin Pens 

Wash hands and clean the injection site with an alcohol pad before using an insulin pen. Allow to air dry naturally, do not blow on the area to increase drying time, as this can recontaminate the area.
Remove the pen cap and clean the rubber pen tip with an alcohol pad for 15 seconds. Peel backing off of the pen needle, then attach to the tip of the pen by screwing on clockwise. Do not overtighten.

Follow the next steps:

  • Remove the clear outer cap and save it nearby, you will need it later to remove the needle.
  • Remove the colored inner needle cap from the needle.
  • On the opposite end of the pen, turn the dial to set the dose.
  • Dial-up 2 units which you will use to fill the needle with insulin prior to injecting.

Insulin tips and how to usePoint the needle end up and push the dial end of the pen completely until the dial returns to “0”. You should see liquid come out of the end of the needle; this means the needle is properly primed and prepared for injection. Priming removes the air from the needle, ensuring that you will inject the full dose.
After priming, turn the pen dial until you see the number for your full dose in the dosing window next to the dial.
Using only light pressure, insert the needle into your injection site at a 90-degree angle. There is no need to press down.  Simply rest the pen on the surface of the skin to avoid injecting too deeply. Pinching skin is not necessary but may be used if desired.
Push the dial button down completely and hold for 10 seconds to allow time for the entire dose to be delivered. You should be able to see that the pen dial has returned to “0” on the dosing window.
Remove the needle, pulling straight back. Reapply the large cap (not the needle cover).  Twist the pen needle until it detaches from the pen. Then place the pen needle into a puncture-proof container and replace the cap on the pen.


Safe Disposal

Place used needles and lancets in a puncture-proof plastic container, like a medical sharps container or a plastic detergent bottle. Never use clear plastic water or soda bottles.
Label the container: Used Sharps, Do Not Recycle. When the container is ¾ full, secure the lid with heavy-duty tape such as duct tape.
Discard in regular trash but be sure to double-check your local health department guidelines first.
In some states, sharps may be turned in at local pharmacies, state buildings, fire and police stations that provide disposal bins or will accept sharps disposal.


Safe Storage

Unopened insulin vials or pens should be stored in the refrigerator, never frozen.
Once opened, vials and pens are to be stored at room temperature (56 to 80°F) for typically 28 days (some types 42 days) and then discarded. Be sure to check individual manufacturer guidelines. Write the date on the insulin pen or vial on the day it is opened or start keeping it outside of the fridge to keep track of when it should be discarded.
Insulin should be kept away from heat and light as this can degrade the insulin protein, reducing effectiveness. Specifically, temperatures over either 88°F or 77°F (depending on insulin type).
Insulin tips and how to useExtra care is needed to keep injectable medicines safe from harm during travel. The cargo compartments of buses, airplanes, or trains, as well as the trunk of a car, might be too hot or cold enough to damage insulin and other injectable medications.
When traveling by plane, keep insulin and supplies with you, preferably in an insulated bag –– never in checked luggage.
When going through airport security, keep supplies in original packaging with the prescription label. Consider having a note from your doctor or pharmacist can also be helpful to avoid delays.

The following diabetes-related supplies and equipment are allowed through the TSA checkpoint after screening:

  • Injectable medication in vials, injector devices, and pen devices. Insulin and other injectable medication must be clearly identified.
  • Unused syringes, when accompanied by injectable medication.
  • Used syringes, carried inside a sharps disposal unit or similar hard-surface container.

Insulin Injection Troubleshooting

Check out this list of common insulin injection issues. If you are unsure about any of the following issues, be sure to contact your primary care provider, endocrinologist or Level2 staff member.

  1. Needle bends or is difficult to insert = dull/overused needle or scarred tissue from overuse.
  2. A stinging sensation when giving injection = cold insulin or you’re using Lantus or Lyumjev
  3. Small (often stinging) lumps on skin surface immediately after injection that goes away = insulin deposited in epidermal layer rather than in fat pad. A longer needle is needed.
  4. Drops of insulin on the skin surface after injecting = failure to wait before removing pen needle from the skin.
  5. Bruised injection sites = needle is too long, injection into the muscle, unsteady needle during injection technique, reused/dull needles, site overuse/lack of site rotation.
  6. Elevated glucose levels despite multiple dose increases:
    • Damaged insulin due to improper storage
    • Expired insulin, insulin not discarded at end of the in-use period
    • Damaged tissue/lack of rotation
    • Need to remove needle cover before injection
    • Failure to prime pen needle before each injection
    • Failure to depress insulin pen button completely to deliver the dose. Check that user is not attempting to deliver the dose by turning the dosing dial backward to zero.  This delivers no insulin. A button press is required.
    • Air bubble in syringe resulting in missed dose, usually due to poor vision or failing to inject air into the vial.
    • Failure to thoroughly mix cloudy insulin by inverting or rolling vial or pen prior to injection.
    • Failure to add air to the vial before drawing insulin eventually results in large air pockets and missed dose.
    • Failure to keep needle tip below the insulin level when the vial is inserted results in air in syringe.
    • Syringe needle bent while drawing from vial.

Insulin Use Do’s and Don’ts

Insulin tips and how to useDo:

  • Rotate injection sites within and among body regions
  • Inject 1-2” from the previous site
  • Use fresh syringes and pen needles each time
  • Keep track of your injection sites
  • Use the shortest needle possible that will reach the fat layer under the skin

Don’t:

  • Inject insulin within a 2 finger (1-2”) radius immediately surrounding the navel
  • Inject into scars, moles, birthmarks or large stretch marks because tougher tissue there affects insulin absorption
  • Inject inner thighs –– there is a large number of blood vessels and nerves, so the region can be painful and prone to bleeding
  • Inject in the skin over a muscle that you will be exercising or into a body area that will be submerged in a hot tub. Both can increase the absorption rate enough to cause low blood sugar.