LifeAfterDx--Diabetes Uncensored

A internet journal from one of the first T1 Diabetics to use continuous glucose monitoring. Copyright 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016

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Location: New Mexico, United States

Hi! I’m William “Lee” Dubois (called either Wil or Lee, depending what part of the internet you’re on). I’m a diabetes columnist and the author of four books about diabetes that have collectively won 16 national and international book awards. (Hey, if you can’t brag about yourself on your own blog, where can you??) I have the great good fortune to pen the edgy Dear Abby-style advice column every Saturday at Diabetes Mine; write the Diabetes Simplified column for dLife; and am one of the ShareCare diabetes experts. My work also appears in Diabetic Living and Diabetes Self-Management magazines. In addition to writing, I’ve spent the last half-dozen years running the diabetes education program for a rural non-profit clinic in the mountains of New Mexico. Don’t worry, I’ll get some rest after the cure. LifeAfterDx is my personal home base, where I get to say what and how I feel about diabetes and… you know… life, free from the red pens of editors (all of whom I adore, of course!).

Sunday, March 18, 2012

The dance

Famous dances in history:

The Dance of the Sugar Plum Fairy.

The Waltz.

The Tango.

The Jitterbug.

The Samba.

And my personal favorite, of course, the Dance of the Seven Veils.

But most of these dances only involve one or two dancers. The Sentry dance is more like a line dance, a square dance, or the Macarena (hey, it lives on at weddings): it involves a number of dancers spinning across the floor together. We briefly touched on it yesterday, but just to be clear on everyone’s job description:

The sensor talks to the transmitter.
The transmitter talks to the pump.
The pump talks to the Outpost.
The Outpost talks to the Sentry.

The shine bone’s connected to the knee bone.
The knee bone’s connected to the thigh bone.
The thigh bone’s connected to the hip bone.
The hip bone’s connected to the back bone.

Got it?

Oh. Wait. Crap! I forgot. The thigh bone can also talk directly to the back bone without going through the hip bone. I hate it when my clever little analogies break down so easily.

This is because Sentry is bilingual. It can talk to both the pump and the Outpost, which themselves don’t speak the same language. Well, saying that the Sentry can talk at all is inaccurate, I guess, as the Sentry is more of a passive listener.

The pump broadcasts its status and its alarms in ultra-high frequency, at 916.5 megahertz. The Outpost speaks to the monitor in different ultra-high language, all the way up at 2.4 gigahertz.

The lower 900 megahertz range of pump-speak is where you find most “cordless” landline phones operating (don’t let the numbers fool you, remember that “giga” is a factor of 1,000 larger than a “mega”); while the two-and-a-half gigahertz range of Outpost-speak is inhabited by wireless computer networks and microwave ovens.

Uh…microwave ovens?

Does that mean the Outpost might fry your little T1’s brain in her sleep? The mySentry manual assures us that “providing that it is used at distances greater than 7.9 inches from the human body” the Outpost is not harmful. (Apparently exempted from the 7.9 inch rule are your hands and wrists.) The manual goes on to quickly point out that the powerful Outpost is still only packs a punch one-tenth the power of a typical cell phone, and that on top of that, the Outpost works in a burst mode, sending out a signal every five to seven minutes. Not that Med-T’s lawyers were worried, or anything.

Still, to be honest, I think you have much bigger things to worry about.

But while we’re on the subject of how these devices communicate, why the difference in language in the first place? Well, even though both signals are scientifically in the “ultra-high” frequency range, the higher (and newer) gigahertz signal carries further in devices of this size. The Outpost speaks the higher frequency simply to give it the greater range it needs to boost the signal so it can be heard by the Sentry at distances of—according to the manual—p to 100 feet away inside your house. I suppose actual range would depend on how well or how poorly your walls are made. I live in a 40-foot mobile home. I’m pretty confident the Outpost can easily reach every nook and cranny in my house and probably out onto the back porch and well into the cactus garden with no trouble at all. The issue of course, is not so much the Outpost’s performance, but the fact that the stupid pump needs to be within a few feet of the frickin’ Outpost in the first place for the Outpost to pick up the signal at all and pass it on.

But here’s where things get interesting. Remember that I told you the Sentry was a bilingual listener? Right. It can hear not only the Outpost, but it can hear the pump itself. Directly. With no Outpost involved. Assuming that Sentry, too, is within six feet of the pump. This is actually a wonderful feature that we’ll talk a lot more about soon. But for now, just know that, no hip bones required, the Sentry can listen to the pump speaking in its native tongue, or it can listen to the Outpost’s much louder voice. And either way it can learn about, and relate to you, the following things that are happening in pump land:

(OK, come to think about it, the Sentry does “speak,” it’s not limited to listening only. While Sentry doesn’t speak to the pump or the Outpost, it speaks to us. It speaks Human.)

It can tell us: What your blood sugar is in real-time. Well, so long as we define real-time to be within the last seven minutes. It can tell us what your sugar has been up to 24-hours previously. It can tell us how fast the sugar levels are changing. Whether they’re going up or down. How strong the pump’s battery is. How many units of insulin are still in the pump. What the signal strength is between the CGM sensor and the pump. When the next CGM calibration is due. How much life is left in the sensor. It can also relay all CGM alarms from the pump: drop or rise rate alarms, predicted highs or lows, and honest-to-God highs and lows; as well as many—but apparently not all—pump alarms, too.

OK. So much for the dance of the components with each other. But now the real beauty begins: How the whole system dances with us.

Next time: Eagerly awaiting an alarm.


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