In people without diabetes, the pancreas releases however much insulin is needed to maintain healthy blood glucose levels—insulin pumps attempt to do the same. These devices are programmed to deliver a small continuous flow of rapid-acting insulin around the clock—basal insulin—as well as on-demand doses selected by the user to cover carbohydrate in meals, snacks, and beverages.
The first insulin pump was designed in the early 1960s and looked like something the Ghostbusters would wear on their backs to blast wicked spirits. Smaller versions started cropping up in the 1970s, but it wasn’t until the mid-1980s that they were designed to deliver precise doses and became user-friendly, according to Nancy B. Dean, director of marketing at Roche, which makes the Accu-Chek Combo pump. “Compared to today’s insulin pump systems, the early insulin pumps were not easy to handle. Some pumps even required the use of a screwdriver in order to adjust the flow rate of insulin, making them difficult to tune and very inaccurate.”
Today, insulin pumps work without hand tools and can fit in the palm of your hand. In most cases, they deliver insulin through an infusion set: tubing that winds from the pump to a needle or cannula—a tiny flexible tube—inserted under the skin. A few tubing-free “patch” pumps, such as the OmniPod, stick to the body and direct insulin through a cannula inserted into the skin beneath the device.
There are eight insulin pumps on the U.S. market, nine if you count the non-electric patch-pump-like V-Go for people with type 2 diabetes (“One a Day,” below). Each pump has its own personality and we won’t cover all their quirks here, but there are some generalities regarding how pumps work. All true pumps require a battery to run—that’s where they get their pumping power. Some pumps have disposable batteries, while others have rechargeable batteries that are powered by plugging them in like a cell phone. They all contain electronics—microchips and such—and a user interface for selecting functions and monitoring insulin delivery. Some pumps double as meters or interact with continuous glucose monitors (CGMs), and so provide a readout of glucose levels as well.