Injecting insulin is part of the daily routine for most people with diabetes. However, when “favorite injection spots” develop and are overused, problems can arise. In this article we’ll cover insulin injection tips and how to keep your sites healthy!
Did you know, that waaaay back in the day, insulin needles could run as long as 12mm? That’s nearly a ½ an inch long! Lucky for us, needles are much shorter and thinner than before. Furthermore, medical studies have shown that the needle length makes no difference in HbA1c values! Yay Science!
So now, using a tiny 4 mm needle, you can achieve your HbA1c targets while avoiding the prospect of painful and risky muscle injections while managing your diabetes. (1,2)
Where Is The Insulin Injected?
For best effectiveness, insulin has to be absorbed into the subcutaneous fatty tissue. Afterward, it is distributed throughout the body to do its work. In adults, this fatty tissue layer is only 2.0 - 2.5 mm beneath the skin's surface. In kids and adolescents that can be slightly less.
Not that thick, is it?
To inject the insulin into this optimal location, the needle must pass through the top layer of skin but not go too deep. The aim of the injection is to get the insulin under the skin, and if possible, avoid backflow, pain or bleeding.
The structure of the skin:
Where Are The Best Injection Sites?
As we mentioned above, you want to inject your insulin into a good pocket of subcutaneous fat. Abdomen, thighs, and buttocks are often ideal injection areas for people with diabetes. Those locations typically offer the best options for optimal insulin absorption.
For manual shots, it’s recommended you create a fold of skin to inject the insulin into. Pen users do not always need to do this, especially if the needles are the super short 4mm length. Either way, below are a few tips to help your injections run more smoothly.
- Most fast-acting insulins can be injected into the subcutaneous fatty tissue, the effect shows no difference whether it be the abdomen, leg or buttocks.
- Long-acting insulins can be injected either in the abdomen or in the thigh.
- When using the abdominal area for injections, stay at least 2mm away from your belly button.
- If you are using cloudy basal insulin, remember to swirl it at least 20 times before injecting it, and aim for the outer thigh or buttocks area.
- After insulin has been injected with either pen or needle, keep the needle in your skin for about 10 seconds. This helps avoid the insulin leaking back out.
QUICK TIP: Remember to “vent” or “prime” your needles prior to use! This means you point the needle away from you and inject 2-3 units into the air to remove any air bubbles in the dose (we like to call that an air shot). You know you have successfully primed when a few drops of insulin come out of the needle.
Which Injection Sites Should I Avoid?
Since the target is to inject insulin where it can most evenly absorb into the bloodstream, the following are all big no-no’s and should be strictly avoided:
- stretch marks
- cuts, scrapes, or scars
Why Is Changing Injection Spots So Important?
The main rule with injection sites is simple.
Do not inject continuously into the same spot.
Repeat injections into the same spot on the body can contribute to the development of lipohypertrophy. Lipohypertrophy is a medical term that refers to a lump under the surface of the skin caused by an accumulation of subcutaneous fat and/or scar tissue which can become thick or hard.
Lipohypertrophy lumps are not only a cosmetic problem. They can lead to absorption issues with your insulin due to an increase in connective tissue. Furthermore, they can be prone to irritation and infection as well.
How Often Should Injection Areas Be Checked?
It is, of course, better to avoid lipohypertrophy in the first place. But sometimes these things just happen. Therefore regular injection site checks are a wise move. Your diabetes team should check your injection sites at least twice a year. This is typically done at your regular check-up and doesn’t require an additional doctor visit.
You can also do it yourself! Using a mirror, you can look for asymmetrical elevations at your favorite injection points. Likewise, run your fingers along the area and feel for lumps and bumps under the skin’s surface. Most of these will resolve if you avoid these areas as an injection location going forward but it’s good to make a note of them so you can be on the lookout for signs of infection.
What is Injection Rotation?
One simple way to avoid injecting insulin into the same spot over and over is to rotate your injection sites. The process is fairly simple. You divide your injection locations (stomach, buttocks, thighs, etc.) into 4 quadrants. Rotating clockwise within them, use a different location at each injection.
Using a rotation approach lowers your risk for lipohypertrophy and helps boost smoother/faster healing in between injections. If you worry about forgetting, there are easy charts, apps, and even temporary tattoos you can get to help you keep track!
What About Insulin Pump Users?
Similar to the injection needles, the trend for catheters for insulin pumps had gone towards shorter cannulas to infuse the insulin in the subcutaneous fatty tissue. But they too should be rotated and moved frequently.
Some insulin pumps utilize tiny steel needles, while others use a flexible teflon cannula. Your pump manufacturer and care team can guide you specifically, but the typical rule is that pump sites should be changed between 2-3 days at the latest.
Source: VDBD injection guide