How to build a better Enlite

A little over a year ago, I wrote a post on How to build a better insulin pump, based on the Medtronic Revel. Since very little has changed from the Revel to the 530G, those wishes/recommendations still apply. But now that I’ve had some time to play around with Enlite, I’ve got some wishes/recommendations on how that can be improved upon as well. My reason for posting this is simple — if nobody knows, nothing will change; but if someone (or some-two, or some-many) makes noise, it’s more likely to be heard. With the goal of being taken seriously, I’m keeping my recommendations somewhat simple and realistic.

* * *

The new Enlite and Enlite “Serter” are a vast improvement over the predecessor. In nearly every way. That goes without saying.

When I first saw the Sofsensor, I concluded that this must have been designed in-house by Medtronic, and not by Unomedical, the Masters (and manufacturer)-of-all-things Infusion Set related (and whose website appears to be out-of-commission at the moment).  Medtronic’s first CGM lacked the characteristics of something being designed by the Masters.

Enter Enlite. It’s better, and it took into account all the feedback received from Sofsensor users. It, too, has been designed in-house. And  sadly, it too lacks some of the characteristics of something designed by the Masters.

Let me be clear: I do think the Enlite is a good product, and this in no way is meant to be criticism worthy of driving someone away from using it. My reason for writing it is so that Medtronic – or perhaps another manufacturer – can learn something and make improvements the next time around. My hope is that they’ll take a look at some of the “little things” that can leave a big impression. And maybe, just maybe, the current product can undergo minor improvements while still being the current product.

Allow me to explain.

1. Cannula length

Unomedical has always offered different lengths of cannula for different body types: one is slightly longer than the other. Enlite has one length of (what I’ve still heard referred to as, though I’m not sure it really is a) cannula. That cannula is really short, and it has a tendency to pull in and out of the skin with regular movement, affecting sensor performance.  This is why it’s so important to tape it down so securely.

I fully agree with the claim that Enlite is virtually painless.  (And since every “painless”  claim is preceded by the word “virtually”, aren’t they all?). But really, it barely hurts at all, and if it does, it’s a brief and sharp sting that goes away quickly.

I attribute the “virtually painless” sensation to the gauge of the needle, as well as the way the sensor cannula/wire is contained WITHIN the needle, rather than stuck to the OUTSIDE where it drags against the newly-punctured skin. (Yes, in that presentation, “drag” was the term that the Med-T presenter used. Yuck). The new sensor is remarkably shorter, but I wish it weren’t quite so short. If it were just a bit longer, that problem of lifting out of the skin might not be such an issue. So in this case, if I were offered two lengths, I’d opt for the longer one without hesitation.

S4-Sensor in Serter

This is the part you never have to see – unless you look at it. The removed pedestal is at the top of the photo.

2. Inserter

Medtronic has taken great pride in their new One-Button-Two-Press inserter and insertion process. It works, but I think they tried to invent a brand new wheel when an already a perfected wheel was present in their catalog. In other words, they should have designed around a previous success rather than starting from scratch, addressing and resolving every bit of customer feedback but not putting enough foresight into the feedback the new device would garner.

The inserter works. I trust it — after all, I signed up for it for the long term — but it’s a bit clumsy to use and still could be better.

I won’t go through the insertion process in detail here, but you can find Medtronic’s instructions elsewhere on the web in PDF or video form.

The first thing you should take note of is how – in both of these company-produced instructional guides, the insertion site is straight down to the ground, with clear sight-line from above, with no body contortions required. That’s nice for demonstration purposes, or if you’re inserting the sensor in, oh, maybe, your THIGH. But (technically) that’s not allowed.

S1-Serter on sensor

The ‘serter resting on the Enlite sensor pedestal

In the real world, we’ve got our neck craned downward, chin-to-chest, looking along the plane – or the contour, as the case may be – of our torso. It’s awkward.But back to the ‘serter.  We want it to rest flat against the skin, with the whole contraption perpendicular to the body.  This way, the delicate sensor doesn’t get damaged by the slightest of side-to-side movement. The ‘serter itself is tall and relatively slender, with an oblong-shaped base. The button is about two-thirds of the way up, on the side. Therefore:

  • The shape of the ‘serter’s base lends itself to side-to-side motion.
  • The device is too tall and the button is too high. Therefore, the thumb has to touch the ‘serter at  button-height, about an inch above the skin, and therefore the fingers can’t rest against the skin to stabilize it.
  • The button is high on the side, so pushing the button is not unlike trying to knock something over. When a force is applied to push the button one side, an equal and opposite force needs to be applied to the other side for balance. In fact, this is the (one and only) part where the Sofsensor ‘serter is better: the button-press is in the same direction as the needle insertion and pressing it won’t threaten to shift the ‘serter out of place.
  • It’s big, heavy, and opaque. Holding it perfectly steady after inserting (to allow the adhesive to stick…official directions say five seconds, I was trained to hold for ten, I’ve also heard 30) without the slightest of movement is not as easy as it sounds.
  • The double-press thing leaves too much room for error. (The sensor is inserted upon RELEASE of the first button press, and the ‘serter releases its hold on the sensor with the HOLD of the second press). I guess the first-part action is to assuage the fears of Enlite newbies, but that only happens the first time or two. The second part, as I understand, is to prevent someone from firing the insertion needle across the room. But the reality is that one needs to press the button on one side, apply the balancing counter-force on the other side, and pull the thing straight away from the body (which, unlike the demo, is not UP), without letting the sides of the inner ‘serter barrel touch the sides of the needle housing.
Enlite Insertion Annotated

Follow the bouncing ball – careful, you might miss something.

This same basic  ‘serter design will also be used for the MiniMed Duo, the combination infusion/CGM sensor site.  Although the button has been moved lower on the Duo (good move), it still leaves me a bit disappointed in what’s coming next.

So how could the insertion process been made easier and simpler? Let’s ask Unomedical, makers of the popular Mio and Inset infusion sites.

Needle size

The all-in-one Mio: Insertion perfection

The Mio is insertion perfection, and it’s really unfortunate that the sensor doesn’t come packaged in a device like this.  It’s lightweight, low-profile, and clear. It has a wide, circular base, so naturally it doesn’t want to rock. The press-points (buttons?), though admittedly on the side, are on BOTH sides, and are right at the base and need a squeezing, rather than pressing, motion. The placement and the means of deployment keep the device centered and balanced. Plus, it can easily be grasped and pressed simultaneously while still using other fingers against the body for extra support. Holding it in place for any period of time is easy; an open palm can rest right over it. Removal of the inserter and needle from the body is in one fluid step – using a grip in the exact center to improve dexterity. Finally, since the needle is the inserter, there are no worries of it becoming a projectile, and the hard plastic cap (if not recycled) suitably protects the needle in the trash*.

* Disposal regulations in your region may vary.

Yes, we can see the needle. And I know the #1 selling point of the Enlite system is that we never see the needle.  But let’s face it, folks. If you’re wearing an insulin pump, you’re probably looking at needles anyway and it’s one of those things you just get used to.  Needles, in and of themselves, are not frightning. It’s just the SofSensor needle that is, and that is (thankfully) gone.

This is possibly the hardest “fix” in this whole list. The mechanics of the Mio inserter would certainly have to change. Possibly the sensor, too. And manual removal of the needle-cover may prove tricky. But I believe it’s worth a shot, and I believe if we could marry these two independently developed pieces, it would generate something much more successful and spectacular than what we’ve got now.

3. The tape

Enlite Tape

Step 1 exposes the middle. Step 2 (my finger is covering one of the 2’s) exposes the edges.

If I were allowed to make one, and only one, improvement to the Enlite system, it would be the overtape.  It’s a weird rectangular shape with a hole in the middle. The tape is meant to give extra adhesive reinforcement to the sensor, but not the transmitter.  Therefore, the little connector-nub of the sensor sticks through the hole. Lining up the tape so that the “nub” sticks THROUGH the hole and not TO the tape is tough (if the tape sticks to it, you’re screwed.  I’ve tried scraping it off with my fingernail, unsure of what damage I may be doing to the sensor). The long end is supposed to rest half on the sensor and half off, which is also difficult to do given that it’s only about a half-inch wide at that point.

But what makes it so tough? Other than the sight-lines that I described above, which you really can do nothing about, it’s the tape itself.  The stuff is super-sticky I must say, and it’s not very forgiving if it touches the wrong spot or folds over on itself. But the way the protective film is peeled away, exposing the adhesive, seems backwards.

With most medical adhesives, you pull off one half of the film and place the sticky half on the body.  Then you pull back the other half, and the whole thing becomes stuck.  Not so with Enlite tape. With this tape, you first expose the middle portion, leaving the two ends protected for you to grasp with the thumb and forefinger of each hand (yes, it’s necessarily a two-handed operation).  Then you lay it carefully on the skin, hopefully in the right spot, and finally remove the protective tabs from the ends.

Did I mention how hard it is to get the sensor connector through the little hole in the tape without letting the tape touch anything? Try scoring a “ringer” in horseshoes without letting the shoe touch the stake. It ain’t easy.

I would much prefer if the protective film were split lengthwise, so you could first get the piece of tape over the back edge of the sensor before worrying about pulling it over the connector. Or vice-versa.

Since this tape is a new creation and not an off-the-shelf product, I’m sure the designers researched the options, and found overwhelming evidence that the middle-then-ends application of protective film was the best one.  I’d love to see that evidence.


4. The flap


The big flap and the little flap

Next to the sensor needle itself, one of the big complaints about the Sofsensor wear was how the transmitter tended to flap (flop?) around on the side and needed something extra to keep in in place.  Medtronic addressed that in this product, and kudos to them for doing so.  Double kudos for shaping the sensor adhesive so that the transmitter doesn’t touch the skin, therefore eliminating the pinch between transmitter and Sofsensor that had caused me much discomfort in the past.

The solution is a little flap of tape that comes up and over the transmitter and holds it into place.  It’s relatively loose, and from what I understand, it’s supposed to be. That way, any inadvertent jostling of the transmitter doesn’t also tug on the skin and risk pulling the sensor out.

But the edge of the tape-flap is a bit sharp and can irritate the skin.  Also, the protective film has a little perforation at the very edge, and sometimes the film tears at the perforation, so the last eighth-inch of the film sticks, meaning the big flap spawns a little flap, unless you go fingernail-to-adhesive to try to remove it.

5. The packaging

Sensor packaging

Which do you think is better protected?

I was happy — no, DELIGHTED — to see each Enlite sensor some in a somewhat rigid plastic package.  It sure beats the flimsy plastic bag that held the old Sofsensors (and its poorly protected needle). I am absolutely confident that the Enlite will not get damaged while in transit or in storage, even if stuffed in a suitcase when traveling. I had no such reassurance with the previous one.

But between the outer package and the inner “pedestal” (which protects the sensor and helps to load it into the ‘serter), it is a lot of plastic. And nowhere on that plastic is the familiar three-arrowed triangle that tells us that this plastic could have a second chance at life.

Not too long ago, I would just look at the lack of recycle-ability and think “that’s a shame”.  But ever since discovering the Mio/Inset sensors came out with their recyclable spaceships, I’ve grown to expect a little more — Unomedical raised the bar with the Mio/Inset, and this is an unfortunate miss for Enlite. (With that said, I confess that I don’t recycle my Mio insertion sets because I use them to protect the needle, but that’s beside the point.)


Recyclable by-product of the Mio


Overall, I think they did a pretty good job designing the Enlite sensor. If they didn’t try to build around the same old MiniLink transmitter, perhaps we would have a more symmetric, balanced design, but that opens up a bunch of other design issues which I’m not knowledgeable enough to comment on. But for now, I’ll take the lower-profile Enlite, with all its quirks, over another system that stacks higher and sticks out farther from the skin.

And all the other benefits that I’ve touted previously.

But I am still left scratching my head.  Why weren’t the infusion-set experts at Unomedical consulted?

Disclosure: Medtronic Diabetes provided me a with Minimed 530G, Minilink transmitter, and Bayer Contour NextLink meter, as well as infusion sets, sensors, and test strips, for a three month trial of their system. I have been given complete freedom to write and distribute my thoughts on the system, without restriction or editorial review by Medtronic- their first chance to see this is on this blog, just like you. At the conclusion of the trial, I promised to return the pump, transmitter, and meter, but the used infusion sets, sensors, and strips are mine to keep. Other than the supplies needed to conduct the trial, I have received no compensation for my participation. As mentioned in my previous post, my trial is now over and I have initiated the process to remain on the system – as a normal paying customer.

Posted on August 1, 2014, in Continuous Glucose Monitor (CGM), Diabetes. Bookmark the permalink. 18 Comments.

  1. this sounds like a big bag of gong show. seriously.
    I absolutely hated and had a myriad of complaints on the last cgm system with Medtronic but this takes it to a whole new level of bedlam!
    I applaud you for writing this concise description without writing “you suck Medtronic”.

    I hope they see this and more than that I hope they use these VALID points to design a new user-friendly and better system.
    The dexcom still ranks supreme.


    • Well, they DON’T suck, and I tried to make that clear without implying the contrary. This is, in no way, an inclusive product review. But it’s the little annoyances that sometimes add up and become frustrating.

      We all have wish-lists or “wouldn’t it be nice if” dreams about every single one of our devices. Nothing is perfect. But if we want to move in that direction, we need to look at every single aspect — every “touch-point”, so to speak — and get it right. It’s like the philosophy Apple has taken, emphasizing the user-experience just as much as the technology behind it. So that’s my motivation here… not to gripe about things, but to offer ideas to make it even better.


  2. One word: ditto.
    OK, one more word: bravo.


  3. Hi Scott–

    One tip from a fellow Eniter–I was confused while reading about your issues with handling the serter and pushing the buttons until I saw the picture of how you’re doing it. I personally “palm” the serter, with my hand over the rounded top part and reaching my fingers down over the top to push the buttons. I don’t have any problems that way with the serter rocking/moving. The only thing I have to watch with this method (per my original training) is to just rest the serter on my skin and not push it down, but that’s easy enough. You might get more stability with this method.

    Otherwise, very good points you have made here. I know what you mean about the corner of the flap tape being sharp and sometimes irritating your skin–it happens to me too depending on my site location. Since they provide so much extra overtape in the box, I have sometimes cut up a piece of overtape and put it under the corners that are bothering me. You know it will stay put for the rest of the sensor life!


    • I can try that palming method, but that leads to some real Twisted Wrister action, and I’m not sure where I’d put my elbow. It’s worth a try though, thanks.

      And you remind me that I completely forgot to write about the fix to the sharp tape-edge, but that should be somewhat obvious — make it a bit more rounded.


  4. Wow, great rundown of everything related to the 530g! Thanks for sharing your insights, and I hope they get more than just a casual look from the manufacturer.


    • This is nowhere near an “everything related to…” post. I tried writing one of those, and it got a bit cumbersome, and also dipped into lots of “your-preference-may-vary” issues, so I abandoned that one. But I totally agree and hope it gets more than a casual look from the manufacturer (great wording, by the way).


  5. Yes, yes, yes, yes, yes!! Seriously, a single use disposable inserter like the Mio would have been AWESOME!

    My only complaint about the tape was that the edge that was supposed to secure the sensor “head” wasn’t very wide, so it seemed to not cover the head as well as tape it down securely enough. I was also one of the ones who reacted to whatever glue they used, so having an option made from the widely available Opsite tape would have been excellent.

    My other issue that I had with it was that the sensor was actually too long for me. It hurt going in and I felt that it was too deep. I wish that they had kept the same angled insertion like the SofSensor was and had just made the sensor wire thinner, or at least updated the SofSensor and made it an additional option for those who prefer angled insertions for sensors.

    Another thing I think would have helped would be if the entire base was plastic, instead of just the head. Granted, it may not be as “comfortable”, but having a strong, sturdy base similar to how the Dexcom is would, in my opinion, make it MUCH better and reduce the likelihood of the lifting that happens, and probably provide a more stable site.



    • Just more examples of how preferences vary. I personally can’t stand Opsite tape because it gets sweaty, feels “crunchy” with movement, and just isn’t very comfortable. And a larger, fully plastic base (i.e. under the transmitter) would make the whole contraption taller, and I think less comfortable. Thanks for pointing out that one-size (or design) doesn’t fit all.


  6. Thank you Scott. You are so informative and the picture solidifies it! You Rock!


  7. I got a letter with my most recent order of supplies warning me about the scrolling issues you pointed out in your How to Build a Better Insulin Pump post. The letter said that Minimed would swap my pump for a new one that doesn’t have that problem if I wanted it (not mandatory though). I think they’re actually listening to you! I found it funny that I got that letter not long after you linked back to that post in this one, which I’m sure they read because of your trial.


    • Really? I remember a notification awhile ago about the scrolling from 0 to Max Bolus … if you did it through the “B” button but not the menu (or possibly the other way around), but not of the Temporary Basal — and I don’t remember anything about replacing the pump.

      I just got a shipment of supplies this week, and didn’t see such a notification (only the one on the change of the look of the packaging) — but maybe I didn’t look hard enough. But if they’re listening, that’s really good to know — and it’s part of the reason I make such a stink over these things! 🙂


  8. Just started the Enlite a week ago and I’m so relieved. I can’t believe Medtronic got FDA approval for the last version, what a worthless piece of crap. It is so difficult to me hassled my a device that’s supposed to be helping you. Multiple massive bruises, bleeding, sensor always getting lost, bad/inaccurate readings making me look even worse than I actually am! Uggh. So, so glad that phase is over.


    • Well, that last version did quite well for me. Not phenomenal (far from it), but well enough that I used it pretty much every day for three years. So while I’m glad it’s over, I’m equally glad that it was available when it was.


  9. Scott, nice writeup, but sorry to say that you’ve missed a huge part of having a CGM in the first place. The critical part of a good CGM system is that the sensor/transmitter can reliably communicate with the reciever/pump. What good are accurate readings when you get multiple lost sensor alarms on a daily basis? This is an area where Medtronic has failed miserably. I have spent hours with the tech support people at Medtronic and they basically have no solution to the lost sensor issues I and many other constantly deal with. Their system is so bad that I’ve had Medtronic Tech Support tell me not to put my 530G in my pocket as the material in my pants will interfere with the signal from the sensor! I’ve also been told to change my sleeping habits so that I don’t sleep on the side that my sensor is on. Really, that’s their solution to a bad RF technology decision, have someone change the way they sleep…….

    In comparison, the Dexcom system can read the sensor from another room, and it never requires recharging batteries. I hope that you try the Dexcom system and see how much better it is before getting stuck with the Medtronic system until your warranty runs out.


  10. Personally I use the tape from the enlite to hold my mio in place it fits beautifully 😉 and I just use a breathable non woven tape over the whole sensor configuration (I cut the flappy bit off first) this eliminates the damp sweaty/itchy feeling under the device.



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