Insulin Pumps: Closer to a Pancreas
Insulin pump products available now in the United States
Insulin pumps are designed to deliver insulin similar to the way a human pancreas does: A little bit trickles out most of the time to handle the body’s constant metabolism needs (called “basal” infusion), while a larger dose (a “bolus”) is given before meals. Unlike insulin injections, pumps can be programmed to automatically deliver different basal rates for different times of the day, just as the human pancreas does.
Pumps also allow users to tailor bolus doses based on factors such as their blood glucose level before the meal and how many carbs they plan to eat. Nearly all pumps include software to help with the math involved in bolus calculations, and some even include food databases to help with carb counting. Still, pumps don’t do it all. They require conscious actions by the user, unlike the pancreas.
From the body’s standpoint, all pumps essentially deliver insulin the same way. But the range of features available from the various brands make them quite different from a user perspective.
With most pumps, insulin flows from a cartridge through tubing and into the body via either a metal needle or flexible cannula inserted just under the skin and held in place with adhesive (“Infusion Sets 101”). The infusion site—along with the tubing and other parts of the system—is changed to a different patch of skin every two to three days. Some pumps require their own infusion sets, while others are compatible with a variety of brands. Buttons on the pump or a remote allow the user to program individual settings and manually select bolus doses.
Not all pumps rely on tubing. One uses an insulin-containing pod (with a cannula) that’s placed directly onto the skin and held in place with adhesive for two to three days. For people with type 2 diabetes, another wearable, disposable device with simplified functions also delivers insulin without tubing (below).
There are other ways in which insulin pumps differ, including by size, user interface, and the capacity to download data to a computer. For people who take very large or very small insulin doses, the reservoir size, increment of units, and number of units per hour that can be delivered are important considerations. Also worth noting: whether the pump’s alarms can be turned off or set to vibrate.
Newer pumps are being designed to work with other diabetes devices. Several pumps have the capacity to wirelessly receive blood glucose readings from specific meters. And three pumps now incorporate continuous glucose monitors (CGMs): The user wears an infusion set and a separate CGM sensor and transmitter. This allows the user to read glucose trend graphs on the pump’s screen.
One particular pump-CGM combination system, the Medtronic MiniMed 530G, includes a feature that triggers the pump to stop delivering insulin for up to two hours if the CGM senses blood glucose has dropped below a certain level and the user hasn’t responded to the alarm. This safety feature is seen as a step toward an “artificial pancreas” that would automate insulin delivery with little or no user input. That’s still experimental, but people have successfully worn prototype models in several research studies.
Insulin Delivery for Type 2s
Insulin Pump: V-Go
Size and Weight: 2.4 x 1.3 x 0.5 in. 0.7 to 1.8 oz. filled, depending on units of insulin used.
Battery: No battery; uses mechanical power source.
Reservoir: V-Go 20: 56 units; V-Go 30: 66 units; V-Go 40: 76 units
Infusion Set: Does not use tubing. Comes with a built-in, 30-gauge, pivoting stainless steel needle with a 90° insertion angle.
Basal Range: V-Go 20: 20 units over 24 hours at 0.83 units per hour V-Go 30: 30 units over 24 hours at 1.25 units per hourV-Go 40: 40 units over 24 hours at 1.67 units per hour
Bolus Range: 2 units per button push; a total of 36 units are available for bolusing
Food Database? No
Meter Interaction? No
CGM Interaction? No
Details: Specifically designed for use in adults with type 2 diabetes. Unlike other devices, the V-Go delivers bolus insulin with button presses, not electronics. Each disposable device is used for 24 hours, after which time users attach a new V-Go. Device is waterproof to a depth of 3 feet, 3 inches, for 24 hours, so there’s no need to remove the patch while swimming or bathing. Does not work with data management software.
As of May 15, 2015, pump manufacturer Asante is no longer in business. If you use the Snap pump, learn how you can transition to a new pump company. It's all here, on Asante's website.