I have noticed in online discussions about insulin pump therapy that prospective pumpers tend to be much more curious about pumps than they are about infusion sets. But once they start pumping, reality sets in: Getting a pump may be like climbing into the driver’s seat of your diabetes management, but finding the right infusion set for your body and your lifestyle is like putting the key in the ignition. You’re getting somewhere with insulin pump therapy only if the insulin is getting into you reliably and comfortably.
What Is an Infusion Set?
Infusion sets—small, thin hollow needles or plastic tubes that function like catheters to deliver insulin into the fat below the skin—are disposable. I’m on my fourth model of insulin pump, but I’ve gone through at least 1,100 infusion sets.
Infusion sets can be divided into two main types: needle-cannula and plastic-cannula sets. Plastic cannulas are usually coated with Teflon, which keeps body tissue from adhering to the cannula and potentially obstructing the flow of insulin into the body. A cannula is a foreign object inserted into the body, so healthcare professionals and infusion set suppliers recommend inserting a new set every 72 hours to avoid infection and maintain optimal delivery of insulin.
Most pump users insert into the abdomen, but the arms, thighs, buttocks and breasts can also be used as infusion sites.
Not All Sets Are Created Equal
Although insulin pumpers have many options when it comes to choosing an infusion set, some practical limitations exist.
First, an infusion set needs a length of plastic tubing to connect the set to the insulin cartridge or reservoir that resides inside the pump. This tubing is usually included in the small package containing the set. A pump’s cartridge or reservoir can have either a Luer-lock (“universal”) connector or a proprietary design unique to the pump’s manufacturer. If you have a Medtronic Paradigm pump, for example, you must use infusion sets designed to work with the Paradigm reservoirs—this specificity may limit your options, compared to the variety of sets available with Luer-lock connectors. (See the chart on page 48 of the May 2005 issue of Diabetes Health. You can also download a printer-friendly version from our Web site at Diabetes Health Charts.) Dana Diabecare II pump users may obtain from Dana an optional adapter that makes the Diabecare II pump compatible with Luer-lock sets, but the pump cartridges are designed to work with Dana’s own infusion sets.
The second limiting factor in choosing an infusion set is that most sets are manufactured by Unomedical, a Danish company that designs and produces infusion sets. As they roll off the production line, a Disetronic Tender, a Medtronic Silhouette and an Animas Comfort are all essentially the same thing: An infusion set that goes in at a 30° to 45° angle, offering a view of the spot where the cannula enters the skin. At present, the Disetronic Tender is available in both the classic 17 mm cannula length and a “mini” of just 13 mm. However, Medtronic Silhouettes and Animas Comfort sets are available with traditional 17 mm cannulas only. Meanwhile, the Medtronic Quick-set is available with either a Luer-lock or a Medtronic Paradigm proprietary connector, but the Inset, marketed by Animas in the United States, is not available for use with Medtronic Paradigm proprietary tubing.
It is important to note, however, that despite its dominance, Unomedical does not have a total monopoly on insulin pump infusion sets. SimpleChoice, a division of Alpharetta, Georgia-based SpectRx, markets its own brand of lower-cost disposable insulin pump supplies. SimpleChoice’s products are not endorsed by the device manufacturers and are used “at your own risk.”
Do the Research, Find the Right Set for You
It’s up to you, in consultation with your healthcare team, to find the infusion set that best suits your body and your lifestyle. Just as basal rates and carbohydrate-to-insulin ratios may shift either swiftly or slowly over time, so may your requirements and priorities when it comes to your infusion set. Your medical history, lifestyle and personal preferences should be considered when you and your healthcare team try to identify the best set for you. The right infusion set is a vital but not necessarily obvious component of successful insulin pump therapy.
Problems and Solutions
Like so many aspects of diabetes management, choosing an infusion set is an opportunity to exercise your problem-solving skills. Here are some solutions to common infusion set problems.
- If you develop an allergy to the adhesive that secures an infusion set to the skin but have no other complaints about your set, you might try a barrier cream like 3M’s Cavilon or a protective plastic patch like Tegaderm.
- Poor absorption from a set can result from a plastic cannula that bends inside the body or from an immune response to the cannula. This can cause erratic blood glucose levels. Choosing a set with a cannula that better suits your physiology may improve your blood glucose control.
- If your set does not adhere well to the skin, your risk of accidentally dislodging a cannula or getting an infection increases. It may be necessary to try a new soap or fabric softener or to use less moisturizer or lotion on areas of your body where you might insert a set. Smith and Nephew’s IV-Prep (available from pump companies) sterilizes the skin and leaves behind a sticky film that may boost your set’s staying power.
- If inserting a new set is problematic, a set that can be inserted automatically may do the trick. See the chart on page 44 and 46 of the May 2005 issue of Diabetes Health. You can also download a printer-friendly version from our Web site at Diabetes Health Charts.
So, Which Set Should I Use?
Your personal choice of an infusion set is just that: your personal choice. Here are some things to consider when choosing a set:
Can you “pinch an inch” . . . or more? Slim adults and small children usually fare better with short (approximately 6 mm) cannulas, while those of us with more padding often benefit from longer-length cannulas (approximately 9 mm). Weight gain or loss may require you to shop for a new infusion set along with new clothes.
What lies beneath
Scar tissue, lipohypertrophy (deposits of fatty tissue resulting from frequent insulin injections or genetic factors), or lipoatrophy (lack of fatty tissue resulting from frequent insulin injections or genetic factors) can necessitate wearing an infusion set in an arm or a leg rather than in the abdomen. If your abdomen is not the optimal site for an infusion set, experiment until you find a site and a set that work well for you.
Do you like to swim or indulge in long, hot baths? All sets should withstand a daily shower, but swimmers and soakers may need to do some research to find a set that sticks through extended water exposure.
How you wear your pump may influence your choice of infusion set. My friend Caroline prefers long tubing (approximately 40 inches) because she wears her insulin pump tucked into her sock, running her tubing down the inseam of her jeans; I choose short tubing (approximately 20 inches) because I like to wear my pump at my waist, and I hate having a yard of tubing stuffed in my underwear. I also like low-profile sets that don’t “tent” the fabric of a fitted top, so I choose sets that may have more adhesive (with a larger “footprint”) and that lie flatter against the body.
You may try a set and discover that you are allergic to it. Fortunately, barrier products like Cavilon cream and the Tegaderm patch can help protect the skin from irritants. People with nickel allergies can use plastic cannulas, and those intolerant of Teflon can usually cope with needle-type sets.
Don’t Forget the Obvious
Is the set you’d like to try actually compatible with your pump’s cartridge or reservoir? If not, is there an adapter available that would make the set work with your pump? If not, is there a similar set that is compatible with your pump’s cartridge or reservoir?