Insulin Pumps and Infusion Sets
An insulin pump (inset) delivers insulin to the body through an infusion set (top left, bottom left, right).
Choosing an insulin pump is a lot like buying a car: They all have one basic function, so your job is to determine which bells and whistles meet your needs. "It's like, does one get a Toyota Camry or a Honda Accord?" says Howard Wolpert, MD, a physician in the Joslin Clinic Section on Adult Diabetes and the director of the Insulin Pump and CGM Program at Joslin Diabetes Center. "These issues are essentially kind of personal, so the individual has to decide." For starters, it helps to have background knowledge of some typical pump functions and features—the ones listed below come standard on all pumps.
An insulin pump is an alternative to multiple daily injections with a syringe or pen. It's a beeper-sized electronic device that continually delivers insulin—by way of a flexible, plastic tube connected under the skin—throughout the day and night, and delivers mealtime doses with the press of a button.
Pumps deliver insulin two ways: in a continuous flow called a "basal rate" and in a quick burst (at mealtime) called a "bolus." A pump's bolus calculator will use your current blood glucose reading, the number of carbohydrates you plan to eat, the amount of insulin currently in your body, and other personalized settings to compute a suggested bolus. The five pumps currently on the market feature multiple bolus delivery options: all at once, extended over an hour or two, or a combination. Most feature a bolus button on the exterior of the pump, which lets you swiftly deliver a bolus without scrolling through the menu on the pump's display.
The minimum amount of insulin you can inject with each basal or bolus delivery hovers in the same range for all pumps, but people who inject small doses, like children or those who are very insulin sensitive, should pay close attention to this specification. If you require a lot of insulin, on the other hand, note the reservoir size; it can hold anywhere from 176 to 315 units of insulin, depending on the pump. The reservoir should last you three days, which is how often you change your infusion set (box, page 51).
If you're trying to decide on a pump for your child, you can rest easy knowing that all contain a key lock option that prevents curious kids from accidentally delivering a bolus or changing settings. Some pumps are waterproof and don't need to be disconnected before swimming or taking a bath.
Reviewing reports of recent boluses and changes to your basal rate can help you adjust your treatment. These records are stored in a pump's memory for a time—it differs among brands, though most store up to 90 days of data. All pumps come with computer software that lets you download and view information, chart trends, and create graphs and tables. While each pump's software varies slightly, the idea is the same: to make it easier for you and your doctor to modify and monitor your diabetes care.
Making an Upgrade
You can buy a new cell phone whenever a new model comes out, but don't expect to constantly update your pump. Most insurance companies won't cover a new pump until your four-year warranty is up. Here's the good news: Some pump companies have special upgrade offers that make switching devices cheaper. Check with customer service to learn the details of the deal and determine if you're eligible.
A pump can make managing your diabetes more convenient, but it takes work. First-time pumpers often take a training course with a diabetes educator who can explain basic pump functions, demonstrate how to attach and detach the pump, and troubleshoot any problems. After that, practice is key. The more you learn about your device, the better you'll be able to tweak your treatment to suit your needs.
Most pumps (except for the OmniPod, which is tubing-free) use an infusion set to move insulin from the pump into your body. The devices are uncomplicated: Plastic tubing connects to your pump, snakes its way to your body, and connects via a sticky patch that holds a short, plastic tube called a cannula under your skin. While all infusion sets are more or less the same, there are a few differences you should keep in mind.
It sounds complex, but the term simply describes the type of connection between an infusion set and a pump. Most pumps use this type of lock to hold the tubing in place and prevent insulin leaks. If your pump uses a Luer-lock connector, you can use any infusion set you like. Many people stick with a brand that's made by their pump manufacturer, but others choose cheaper brands that aren't associated with an insulin pump. MiniMed's Paradigm and Sooil's Diabecare IIS pumps don't connect to Luer-lock infusion sets, but use their own sets instead. Paradigm users who want to choose from a wider range of infusion sets can get a reservoir (from the company Fifty50 Medical) that fits into the Paradigm pump and makes it compatible with
all Luer-lock connectors.
Infusion sets transport insulin to your body with the help of either a flexible plastic cannula or a small steel needle, and your choice is a matter of personal preference. (Very few people use a needle that's left under the skin.) Your size and level of activity will help you determine other factors like the cannula or needle's length, angle, and gauge. For instance, a thin person who has little fatty tissue might pick a short cannula, while someone larger may need a longer one.
You can insert your infusion set manually, by sliding the needle or cannula (with the help of a removable needle) under your skin. Many infusion sets use insertion devices that, with the press of a button, place the needle or cannula under your skin and attach the adhesive.
There will come a time when you'll need to take off your pump—if you go for a swim, for example, or play a rough game of football. (Note: Some pumps allow you to swim and bathe while connected.) Instead of removing your entire infusion set, you can briefly disconnect the pump and tubing. For most infusion sets, you'll detach the tubing directly at your infusion site, leaving the cannula under your skin and the adhesive in place. Other infusion sets allow users to disconnect a few inches away from the infusion site; a short trail of tubing remains attached to the adhesive. People with shaky hands or visual impairment benefit most from this type of disconnect since it reduces the chance of pulling at the adhesive and dislodging the cannula.
Most infusion sets offer a range of tubing options. Your height and infusion site location will determine the tubing length that is right for you.