Where is the best place to insert my pump set or CGM sensor?
An infusion site is the place on your child’s body where the infusion set (the part of the insulin pump that delivers insulin under the skin) is attached. A sensor site is the place on the body where a CGM or Libre sensor is attached.
It’s important to choose an effective pump site, as this impacts how well insulin is absorbed (which, in turn, affects how well blood glucose managed). Also, you can reduce the risk of many pump-related problems (soaring highs; unpredictable BG swings; site infections; middle-of-the-night set change when things go sideways) by choosing a good site, and then taking good care of that site. Choosing an effective sensor site is equally important, as the accuracy of the glucose readings is affected by the area in which the sensor sits.
Location, Location, Location…
The key to effective and consistent insulin absorption is that it is delivered into the layer of fat below the skin without going as deep as the muscle below. Just as we discussed the implication for needle length in the injected insulin section, the same applies here to insulin infused by an insulin pump: as the length of the cannula affects the depth at which the insulin is infused, it is important to choose an infusion set with an appropriate cannula length for your child’s age and body type. (Your child’s diabetes health care team is a good resource for recommendations on cannula length.)
To put this issue of cannula length into perspective… The distance between the surface of the skin and the muscle (at a 90 degree angle to the skin surface) may be less than 4mm in some children, particularly in preschool and early-school-age children. Yet most infusion sets have a cannula length of 6mm or longer (especially for sets with an angled entry). If there is not enough fat below the skin before you hit the muscle layer, there is an increase chance of the cannula bending and “kinking”, which is likely to lead to erratic absorption and, therefore, unpredictable blood glucose readings. (I know firsthand the frustration of this scenario! ~Michelle) In addition, the stinging sensation that some kids experience upon bolus delivery is largely related to cannula length – an appropriate length is likely to reduce stinging.
So in addition to infusion set choice, the location on the body is also important. A good site will have enough fatty tissue so that the end of the cannula sits in the target area of fat – to test, see if you can “pinch an inch” – if you can, that site may be viable.
The following body parts are commonly used as infusion sites (listed in order from the quickest, most consistent absorption at the top of the list):
- The abdomen (tummy) tends to absorb insulin most quickly and consistently
- The top of the buttocks (bum); or
the fleshy part of the hips (“love handles”), avoiding the area right over the hip bone
- The back of the upper arms; or
the outer thighs (avoiding lean areas on the front thigh, over the quadriceps)
Keep in mind that exercising a muscle group where the infusion set is located will increase insulin absorption. For example, if your child does tricep presses lots, a site on the back of the arm will result in increased insulin absorption and, possibly, increased risk of low blood glucose.
For children, the bum and belly are commonly used for infusion sites. They are out of sight, out of mind, and have a relatively large area of skin to work with.
The above holds true for effective CGM and Libre sensor sites also. A good sensor site is one that is bathed in interstitial fluid, so that the sensor can get an accurate reading; the sensor should sit the layer of fat below the skin without contacting the muscle below (which can cause the sensor wire to bend, leading to sensor failure). The tummy, upper buttocks and back of the arms are approved sites for different sensors. Check your owner's manual for recommended sites for each device.
For individualized information on selecting an infusion or sensor site, please discuss this with your child’s diabetes health care team.
Tip from the Trenches
For both of our boys (whose bodies are quite lean), the bum was the only body part that worked very well (or at all!) for infusion sites. This is/was true for us through the preschool, elementary years and into early adolescence. The only snag in using bum sites is that it’s possible to pull out an infusion set when little hands are pulling pants up and down – particularly, for very young children, during the early stages of independent toileting. At 3 years old, our son pulled out more than one set going to the bathroom, and I hate to admit that I pulled out a few myself. These instances were, however, relatively rare, and the possibility exists for sites on any body part. And with practice, both my son and I learned to reduce the risk. ~Michelle (and Danielle)
Rotation, Rotation, Rotation
Just like when you inject insulin, when using an insulin pump you want to use different infusion locations to avoid over-use of the same piece of real estate (overuse will lead to scar tissue and inconsistent insulin absorption).
When choosing your next site location for an infusion set or CGM/Flash sensor, You are less likely to overuse a given spot if you rotate across one side of the body in rows, rather than using random selection or alternation (jumping back and forth, for example from the right side of the belly to the left and then back to the right). For example, you could move from the far-left side of the left buttock, in a row across to the far-right side of the right buttock, before moving down one row and doing the same, moving again from left to right.
Also, if you leave the last infusion set in while you place the next set beside it, you will be more likely to place the new one in an effective position.
How’s the View?
You may also want to consider aesthetics… will the infusion set be hidden by clothing, or will others be able to see it? Is it important to your child that the infusion set not “ruin the look”? For example, if your daughter likes to wear skirts above the knee, the thigh may not be the most ideal site. Similarly, if she likes to wear tank tops or sleeveless tops or dresses, then an arm site may not be to her liking.
On the other hand, she may want to show off her “bling”. Many kids like to dress up their infusion sets with stickers or jewels. Patch pumps (for example, Omnipod) are particularly amenable to this, as the infusion set has a nice flat surface that accepts bedazzling nicely. Set decorations are a great way for children or teens to personalize their look and express their own style.
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There are some particular areas that you would be wise to avoid when choosing a site for an infusion set:
The new site will ideally be located a minimum of 2 finger widths (or 2.5-5.0 cm) away from the previous site, to avoid any tissue damage or scarring that may have occurred as a result of the last infusion set (as healing and scarring is likely to affect insulin absorption).
That being said, the closer together you can place successive sets, the less “real estate” is used up, and the more sites you can get from one area of skin over the next several set changes. Like everything else, it’s a balance.
It’s wise to stay away from:
- scar tissue from old wounds,
- any healing wound,
- previously infected sites (avoid for 1 month),
- the belly button (2 finger widths away) ,
- directly under waistlines, belts, underwear edges (as these may rub on the infusion set, causing irritation or causing the set to come out),
- highly exercised areas,
- lumpy areas (lipohypertrophy)
- dented-in areas (lipoatrophy)
- bruised areas,
- tattoos or piercings, and
- bony areas (ex. right over the hip bone)
In coordination with information you’ve received from your child’s diabetes health care team, take a moment now to think about possible infusion sites for your child, or possible new sites if you are looking at branching out…
What type of body does your child have, are there areas where she has more padding, which may be appropriate for an infusion site?
Are there any healing or old wounds to avoid in this area?
What type of activities does your child tend to do, and will this change what you see as the “best” place to start? (For example, a teen who lifts weights may find that an infusion site on his arm gets in the way, and may have different results from an infusion site on his arms than if he did not lift weights. A child who often does bum drops on the trampoline may prefer a tummy site to a bum&nbps;site.)
Does your child prefer that the set will be hidden by clothing?
Does your child have another preference that you may not have thought of?
Now that you’ve chosen one or more potential infusion sites, next steps include:
The above information was significantly modified, with permission, from The Alberta Children’s Hospital Diabetes Clinic information handouts.
The above information was reviewed for content accuracy by clinical staff of the Alberta Children’s Hospital Diabetes Clinic.
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