News broke the other day that Tandem Diabetes had gobbled up 51 patents belonging to Smiths Medical ASD, the folks who made the Deltec Cozmo pump that's been off the market for almost four years now. Officials from both companies are tight-lipped on what this means, but it seems to imply that future versions of the slick new Tandem t:slim pump might utilize some legacy Cozmo technology...


Meanwhile, we got word in early January that Tandem and the JDRF are working on a dual-chambered infusion pump, and Tandem is already working to eventually integrate its pump with the Dexcom CGM sensor, so the future of this young company (est. 2006) should be an interesting one!


All this recent news makes us wonder: How solid is the first-generation t:slim, which will serve as the foundation for future products? Many in the Diabetes Online Community (DOC) have begun posting day-to-day impressions of this new D-device that got FDA approval in late 2011 and hit the market last summer -- including our columnist and correspondent Wil Dubois. Here's Wil's overview of his experience so far:


I've been pumping with the Tandem t:slim, the new Applesque touch-screen insulin pump for more than a month now.

Believe me, I know what you're thinking... It's the same thing that's been on the minds of everyone who doesn't have this latest gadget but has been googly-eying and drooling over its sleek slender style, so unlike traditional button-interface insulin pumps.

Is there anything special about the t:slim beyond the pretty face? Is the t:slim just about the looks and not really a better breed of insulin pump?

Those are the questions I've been mulling myself lately, and what I'm hoping to answer for you now.

So here we go.

First Impressions

Tandem makes a big deal out of the smallness of their pump, claiming it's the size of a credit card. At roughly two inches by three inches that's technically true, but what makes a credit card small is its thinness, not its footprint. In reality, t:slim isn't much slimmer than the competition. T:slim clocks in at 0.6 inches thin while the Animas Ping is 0.76 inches thick.

Is that thin enough to carry the pump in the front pocket of your blue jeans, like in all the Tandem PR shots? Yep. You sure can. That's how I've been carrying mine, although it's only one of many options.

The t:slim is lovely to see and to hold. It feels solid, and well made. The color screen is highly responsive to the touch, and it uses that color intelligently. The pump has no feature allowing you to change the screen brightness, but it's well optimized for most lighting conditions: The black background keeps it from blinding you at three in the morning, while the icons and lettering are bright and contrasty enough to make the pump easy to read even in bright indoor lighting. Outside in direct sunlight—at least a mile above sea level where I live—the pump can be a little difficult, but not impossible, to read.

I do find the "buttons" on the touch pad to be a hair on the small side for me, and my big fingers sometimes punch the wrong menu or enter the wrong information. Of course, I'm a luddite who only got my first touch-screen device this last summer, so some of my problems here may be lack of experience.

And speaking of touch-screens...

Risking a Butt-Bolus

Police nationwide have been plagued with an epidemic of butt-dialed 911 calls, false alarms caused by people sitting on their cell phones. According to the New York Daily News, New York City's emergency center receives over 10,000 butt-calls per day. If we can't keep our phones from calling the cops when we didn't intend to, what's to prevent us from being killed by a butt-bolus of 300 units?

As a safety feature, the t:slim needs to be "unlocked" by pressing the only "real" button on the device (on its top) and then tapping three targets on the touch screen in rapid succession. If the screen is touched anywhere else during this process, the pump's screen goes dark again. The process is easy, and actually—bizarrely—kind of fun. It's got that Mission-Impossible-electronic-hacking feel to it. It doesn't slow me down at all when I need to use the pump, and it works; my t:slim hasn't dialed the New York City police even once since I've had it.

Of course, it's only been a month.

Scrolling = Obsolete

While Medtronic pumps can get data from specially built versions of the old BD, OneTouch, or lately, Bayer meters; OmniPods have a built-in FreeStyle meters; and the Ping talks to its OneTouch meter—the t:slim doesn't integrate with any BG meter at all. Even before the t:slim box arrived, I was dreading the thought of having to enter BG data manually for corrections, and worried that I might skimp on doing this as often as I should because entering data manually is such a pain.

But what I hadn't gotten the 4-1-1 on, until I did it myself, was that entering data ain't what it used to be. The t:slim's touch pad does away with the need for endless scrolling through a long chain of numbers with an "up" or "down" button. Instead, you just enter whatever number you need. Directly. 1-2-3. Dial-a-bolus.

So yes, data entry is manual, but not in the old sense of clicking incessantly up and down, over and over, till you get to the number you need.

On-The-Fly Meals & Friendly Programming

Entering carbs for a meal is just as fast as entering a BG, and in another time-saver, you can add up your carbs on the fly. The screen used to enter carbs for a meal bolus is itself a calculator, letting you enter the carb count of each individual food item as you figure it out. The pump keeps a running total for you—no more writing your food math on napkins—so now (maybe) you'll be able to eat before your food gets cold.

Then, there's the whole menu setup of the t:slim that clearly got its share of attention during the design process.

There aren't endless pages of menus to go through, and in most cases nearly all the options appear on a single screen. Again, no scrolling.

A ground-breaking feature of the t:slim is that basal rates, correction factors, carb ratios, and target BGs can be viewed all together in one place called a "profile," instead of being in four separate places. The pump holds up to six profiles, each of which can have up to 16 time segments, and you can copy an existing profile with a couple of screen taps to make near-duplicate profiles rather than having to re-enter everything from scratch. Whew!

Sadly, like most other pumps on the market, you still must manually switch between profiles. For example, if you have a weekend profile, you'll have to activate it yourself on Friday night.

I was also frustrated at the extraordinary number of "are you really sure" type of warning screens when taking insulin. To cover a meal and take a correction bolus requires you to navigate through four such confirmation screens. And when I enter an out-of-range blood sugar into the pump, it first asks me if I want to correct it. Of course I want to. Why else would I have entered it in the first friggin' place?

All Praise IOB

CoZmo fans rejoice! Insulin On Board (IOB) is baaaaaaaaaack!

The t:slim, unlike the rest of the pump pack in recent years, tracks all insulin given, not just insulin for meals. Better still, it displays this info prominently on the home screen where you can check it without even unlocking the pump. My informal poll of a half-dozen new t:slimers found this to be the No. 1 new indispensable feature. We could spend an entire post talking about IOB tracking, and how to use it, but suffice it to say it's one of those things that once you have it, there's no going back.

Power Fear

The t:slim is rechargeable. Every other pump I've ever worn was battery powered, and carrying a few spare copper-tops was no big deal. But a pump is a life support system. It wouldn't kill you if your cell phone went dead—OK, for some people it probably would—but can you imagine the terror that would strike your heart if you read "15 minutes of power remain, recharge immediately" on the screen of your insulin pump? What if there were a blackout? What if you were lost in the woods?

Of course, my daily life is full of rechargeable devices: cell phone, iPod, camera, laptop, and razor to name a few; as is my diabetes life with a Dexcom CGM and a rechargeable glucometer; and they rarely give me trouble.

Tandem recommends that you "top off" the t:slim's battery daily, and apparently this doesn't harm the battery's lifespan. I plug mine in for 15 minutes a day when I'm in the shower, and I don't think it's ever gone below 95% since. In theory, the battery lasts for seven days if you get lost in the woods.

And if you're planning to be in the woods for more than seven days, you can use a charging pack or solar charger. T:slim can be charged from a wall, a computer, or a car with a USB cable—and the gear needed to do all three is included with the pump.

That said, one thing I would fault Tandem for is giving us a plug for the car and a plug for the wall but only one cable. WTF? A quick call to Tandem and a $9.95 charge on my debit card fixed the problem, and I now have a complete backup charging system in my glove box. If I get lost in the woods it will likely be in my Jeep anyway, and if there's a blackout I can recharge in my driveway.

Make a Cup of Coffee, Read the Newspaper... 

One of the worst aspects of the t:slim is its slooooooooooow site change. The pump features a 300-unit bag-like insulin reservoir rather than a syringe. The pump fetches insulin from this bag as needed using micro-pump technology. Tandem touts this as a safety feature as it places a physical barrier between the wearer and a potentially fatal overdose of insulin -- but this also limits the speed at which the pump can fill the infusion set tubing.

Are you sitting down? The time it takes to prime a 43" set is... six friggin' minutes.

Oh well, at least it gives you time to brew your morning coffee, check the weather and your email, and get a manicure. On the bright side of site changes, the t:slim uses the industry standard Luer lock connection, meaning any brand and style of set can be used, except those with proprietary Medtronic Paradigm connections.

My Final Word

Overall, I think the t:slim is a fine device. It's more than just a garden-variety pump with a pretty high-tech face. Tandem has led the charge back to IOB tracking, has pioneered a new profile-based method of pump programming, minimized menus, eliminated scrolling, designed a truly user-friendly interface, and wrapped it all up in a small box that is generally fun to use. The fact that it looks cool is just icing on the cake.

Yes, there are things missing and some that Tandem could have done a little better. For one, the computer software that it goes with it is still being held up by the FDA. This probably isn't a big deal for veteran pumpers, but will be a real headache for newbies trying to sort out their settings with nothing more than long delivery history logs on the pump itself to work with. You can't predict how long the FDA may take on anything, but Tandem surely could've timed this better.

Am I in love? No. Actually, I'm considering abandoning the t:slim. It has nothing to do with the little incident I had with a reservoir, or with the well-publicized scary low that I had that might, or might not, have had anything to do with this pump.

It's the sheer volume of  "are you sure" screens that stand between me and my insulin that's starting to make this pump feel like more trouble than it's worth. The Tandem folks tell me that new FDA regulations mandated this level of caution, but it's tedious, especially when I'm tired. Please... I just want my damn insulin... These numerous caution screens are starting to grate on me. 

So I'm thinking about going back to my insulin pen. For real. It never asks me if I'm sure I want the bolus I just dialed up. Not even once.

Much less four times.

Disclaimer: Content created by the Diabetes Mine team. For more details click here.


This content is created for Diabetes Mine, a consumer health blog focused on the diabetes community. The content is not medically reviewed and doesn't adhere to Healthline's editorial guidelines. For more information about Healthline's partnership with Diabetes Mine, please click here.