So before we really dig into our story, we need both a common language and an understanding of the cast of characters in our ongoing drama. Or maybe it will turn out to be a comedy. Hopefully, not a tragedy. But, as Shakespeare said, “all the world’s a stage…”
The Cast of Characters (Working outwards from the skin to the nightstand):
Technically called the Sof-Sensor Glucose Sensor (registered trademark, yada yada yada—Med-T is a ®©™ happy company), this is the needle-like miracle of modern technology that nestles in your subcutaneous body fat, bathing in interstitial fluid for an FDA-approved period of three days. Of course, these bad boys are expensive with an official retail price $42 each, so no one in their right mind wears them for only three days. Six and nine are the most common wear-lengths, although I found one crazy person online claiming to have worn one for nearly a month. We’ll talk a lot more about the wear-length issue later. The Sof-Sensor is the first-gen workhorse of Med-T CGMs, being originally FDA approved waaaaaay back in the summer of 1999. It’s been on point through about six generations of their gear, depending on how you count generations. The sensor is a microelectrode, made of, no shit, gold. It’s then coated with glucose oxidase, enzymes, and several layers of “biocompatible membranes.” So really, it’s nearly a living thing with a heart of gold. Using the magic of bio-electrical-chemistry it can determine the relative level of glucose floating around in the water between your cells. The sensor is the star of all CGM systems, it’s what makes CGM possible. The basic structural design of the Sof -Sensor hasn’t changed for over a decade, but improvements to the coating process and smarter algorithms in the gear that interprets the sensor’s data have improved accuracy a great deal over the years. The sensor slides under your skin with the aid of a large-ish guide needle that’s then removed. A flat clear-purple plastic hub remains on the surface of your skin, stuck firmly in place thanks to a thin sticky-tape pad. The hub has a connector for the next actor:
The MiniLink transmitter
Hence forth simply called either the CGM transmitter, or more commonly here at LifeAFterDx, the “seashell” due to its resemblance in size and shape to something you might find on the beach. It’s an aerodynamic rechargeable device that snaps onto the sensor’s hub. The seashell both stores, and wirelessly transmits, sensor signals to some other device, in this case the:
The Leading Lady—the MiniMed Paradigm Real-Time Revel Insulin Pump
A name which does not fit on the marque, so I’ll simply call her the Revel or simply the pump—at least until such time as she reveals enough of her personality to me to rate an official LifeAfterDx name. Now insulin pumps are pager-sized devices that… What? Oh dear. That’s right. I’ve been writing about insulin pumps for so many years I’ve forgotten that pagers have gone the way of the pterodactyl and the stegosaurus, and that most young people have no clue what a pager is, or what size it was. Hmmmmmm…. give me a second… Ah! OK, a pump is a cigarette pack-sized electronic device that makes insulin delivery a helluva lot easier and more accurate. The pump carries fast-acting insulin only, covering the body’s basal needs with a constant pre-programed variable drip, and delivering more insulin on demand for meals and corrections. It doesn’t do much of anything automatically. Pumps aren’t smart. A pump might replace your pancreas, but it doesn’t replace your brain. It’s just a fancy syringe. Although technically part of the Paradigm line from a few years ago, the Revel is a very different beast on the inside from its predecessor. Better menus, more sophisticated CGM features… I’ll talk a lot more about this later. The pump doubles as a display monitor for the CGM, so although we often refer to such systems as “CGM enabled pumps,” it’s really not true. The relationship is more parasitical than enabling. The CGM controls no pump functions at all here in the States. The pump simply displays CGM data and serves as home base for the CGM alarm system; but as such, results in one less box on my belt, and that scores a lot of points with me. The pump has an entire supporting cast of its own including the disposable infusion set made up of an insulin reservoir, tubing, a connector, an insertion site assembly, and a cannula to deliver insulin through your skin and into your body. She also has a consort in the form of a dedicated blood glucose meter that can whisper in her ear. The meter, too, has own supporting cast of strips, lancing device, lancing needles, and a horribly large belt case. But for now, know that like a game of Grapevine, the Revel takes the CGM signals and passes them on to:
So Med-T had a problem when they wanted to develop a remote monitor for their pumps. The problem was/is that the transmitter in the pump isn’t worth a crap, largely because it never needed to be worth a crap. It’s original function, I imagine, was to transport data from the pump to a computer system for analysis. You don’t need much of a transmitter to do that. In point of fact, the transmission range for the Revel pump is around six feet. A supermodel wearing a Revel in her bra can barely transmit her data to the floor she’s standing on. So what to do? The solution is one of two parts of the mySentry system (technically there are three parts, but one part is just a power adapter)—a signal-booster called the Outpost. The Outpost is about the size of a nightlight and plugs right into a wall plug. Actually, it doubles as a night light. And, I gotta say, the Outpost is a cute as a button. But I think I need to be very clear about what the Outpost is not, more than what it is. It does not turn your home into a CGM wireless hotspot that’ll pick up your pump’s CGM signals as your roam around your house in your underwear. The Outpost is a powerful signal booster, but it’s boosting a weak signal. The Outpost will amplify a Revel’s anemic signal and send it up to 50 feet away; but to do so it has to be within six feet of the pump to hear the signal that it’s going to boost and pass on to:
The Leading Man—the monitor
Oddly, this heart of the mySentry system doesn’t have a registered trademark name at all. It’s only known as the monitor, or MMT-9101 to its friends. And even though mySentry is technically the name for the whole system: monitor, Outpost, and power supply, as the monitor really is the one that stands guard, I’m going to call it the Sentry here at LifeAfterDx. The Sentry looks like a Star Trek: The Next Generation sickbay device stuffed into a 2001: A Space Odyssey box. It’s old-fashioned modern-looking if you know what I mean, about seven inches left-to-right, and five inches tall. The buttons are flat, smooth to the touch, but not at all like a modern Apple touch screen. Sentry was designed and sent for FDA approval long before iTouch technology even existed in a basement at Cupertino. Still, the ghostly buttons are responsive, requiring only a whisper of a touch to operate. The screen is color, and shows what’s happening in Pump Land. In the coming days we’ll talk about every button, every screen, every feature, and every noise this gentleman can make.
The supporting cast includes:
A triple-A powered charging unit for the seashell, a USB antenna for downloading the pump to a computer, a belt clip or holster for the pump, a test plug for the CGM, a horribly designed inserter for the CGM sensors, manuals, quick-start guides, batteries and more round out the cast—and I’ll introduce you to each of them later, as they make their appearance on the stage.
Next time: the Dance. Or how all the parts play together.
PS: happy St. Patty’s Day to all of you people green with envy. ;-)
Thank you for letting us know about the different parts and the downfalls as well as the positives aspects of these types of the units. I enjoy your blog and you put out very informative peices.
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