Medtrum’s Nano – an alternative patch pump

For a while now I’ve been intermittently flipping the occasional patch pump in between my normal use of my Roche Insight.

To this end I’ve been using the Medtrum Nano patch pump.

Long time readers of this site will know that I’ve tested the company’s CGM systems on multiple occasions and found them wanting. Pumps, on the other hand, don’t require the same level of chemical and software engineering, so would they be any better?

Medtrum ship the pump separately from the CGM, but in most of their advertising, they show the Easypatch app, which allows control of the pump via phone, as well as collection of CGM data within the same app. You can guess where they’re going with this…

The pump comes in 200u and 300u versions, as shown in the image below. I’ve been using the 200u version.

For full disclosure, Medtrum gave me the first set to try, however, I have since bought more of them, as it turned out that they work reasonably well and have the added benefit of being supported in AndroidAPS.

In terms of size, they are slightly smaller than an Omnipod Dash pump. The picture below provides a comparison.

Features

The main “features” of the Nano are the cannula, the two part pump and the connectivity to your phone.

Cannula

Unlike the Omnipod, the Nano has a 90° steel cannula that is manually inserted via a button on the top of the pump, after you attach it to your body. The cannula is very fine (32G or 0.235mm ) and 6mm long. Some might worry about occlusions with such a fine needle, but so far I’ve not experienced anything. Application is straightforward and wear has been surprisingly comfortable, however, I am tall and have a little extra body fat. I’m not sure how users with lower body fat might find it.

The pump expires after 3 days wear plus eight hours grace period. With a teflon cannula, I wouldn’t expect this to be a problem, however there are questions over the sense of this with a steel cannula. Historically, advice has been to remove steel cannulas after two days, and this isn’t because of reactivity.

The challenge with steel is that it has a sharp tip in order to insert it, which remains in the body until the cannula is removed. Any pressure or movement of the cannula in the tissue causes the tip to damage local tissues. You can feel the cannula if, for example, you apply pressure on it when it’s underneath a backpack.

There’s an open question as to whether the larger surface area of the pump plaster keeps the steel cannula more secure, so that three days of where is less of an issue, but there doesn’t seem to be any data related to this.

On the other hand, data from pigs suggests that while tissues next to a steel cannula are less susceptible to inflammation than those next to Teflon, tissues close to the sharp tip are more susceptible to scar tissue. It’s something that users may want to consider, especially if using in younger people.

Diabetes is a marathon and not a sprint, so the less scar tissue, the better.

In order to remove the pump, you first have to release the cannula. This is done with a tool like the one used to remove a SIM tray on a phone. You have to stick it into a small hole in the depression mechanism, and the cannula lifts out of the skin making pump removal far less of a risk.

While this is smart thinking, as ripping a steel cannula out would be painful and messy, it’s also not the easiest to do when you can’t see the pump. It enhances the feeling that this may not be suitable for people with mobility problems.

The two part pump

The pump consists of a pump base, which houses the smarts and Bluetooth connectivity module for the pump, and a reservoir patch, as shown in the below image.

When the pump expires, the base is removed and is then passed to the next pump, removing any need for re-pairing or serial number input, which is a nifty feature. I’ve found this to work well.

In theory, at least, this means that when the pump is finished, you retain the electronics, remove the steel cannula and put it in a sharps bucket (it’s tiny) and then dispose of the reservoir. It would have been nice to see Medtrum offer a recycling service similar to the one Omnipod provide, rather than just binning stuff.

Phone connectivity

The Nano can be controlled either via an app on your phone or via a dedicated handset. I imagine that most people go for the app. This app also integrates Medtrum’s Nano CGM. I’ve discussed the app elsewhere, and in all fairness it’s not bad.

The other phone connectivity available is an integration with AndroidAPS, which is how I’ve used it. That’s a pretty seamless experience and uses a pairing process that’s essentially identical to the proprietary app.  It’s proven to be very effective.

Issues and concerns

As ever with pumps and things that are attached to your body, there are always annoyances that cause people concerns. In the case of the Nano, these fall roughly into four areas:

• Communication errors
• Adhesive issues
• Reliability concerns
• Other issues

We’ll look at each of these items separately.

Connectivity errors

The pump base can lose connectivity to the phone (whether you’re using the Medtrum app or AndroidAPS). If you look around the various online forums, this seems to be an issue more with slightly older (pre-mid 2023) pump bases. What this means is that any change that you might have expected the app or AAPS to make won’t have happened.

This is less likely to be an issue with the Medtrum app, as you’re manually doing things, meaning you see when it’s not connected. More of a problem if you miss something with AAPS and a low basal, for example, stays in place for longer than expected.

The only resolution I found for this was to replace the entire reservoir, which is a little frustrating.

Adhesive issues

A number of people have reported bad responses to the adhesive used by Medtrum. Reactions to adhesive are to be expected, so it comes as no surprise. What isn’t clear is what proportion of current users that makes up, but if we apply the usual rules of the internet, that generally it’s people with problems that make the most noise, then I’d imagine the proportion is consistent with other pumps and cannulas.

Medtrum offers advice on how to deal with it, so it’s clearly something they’re aware of, but that’s to be expected of a patch pump supplier. I personally didn’t experience any major adhesive reaction.

Reliability concerns

A quick search of the internet raises one thing that seems to stand out. Battery failure of the reservoir. This is also something that I experienced. When this happens, the unit dies prematurely and a replacement is needed.

Once again, it’s something that becomes quite obvious when using the pump manually, but with AAPS, appropriate alarms are needed to ensure a user notices that the phone and pump aren’t communicating.

Other issues

I mentioned early on that when pressure is applied to the pump, whether that’s by a chair, backpack, or something else, it can be uncomfortable at the cannula site. That discomfort can also be found elsewhere around the rim of the reservoir body.

As the above image shows, the pump has quite a hard “edge” and uneven pressure can generate irritation.

As the second image of these two shows, the corner and bottom edge of the pump have dug into the skin due to pressure from a backpack.

The area around the cannula also looks a little angry.

What are the takeaways?

The Nano pump is a nice package, there’s no denying that. It does have some shortcomings, as I’ve mentioned here.

The size is great, and steel cannulas tend to maintain consistent flow over their life. I’m not convinced that I should be using a steel cannula for 3 days plus in the same spot though. I’ve seen no data that counters this view.

The Nano is also a relatively inexpensive pump compared to many, which is also a factor in its use.

Possibly the best part is the connectivity with AndroidAPS. I know a number of others who use it in this way.

As I mentioned, I like it enough to have a box to use when I’m looking to not use a tubed pump. I’m not sure I could comfortably use one all the time. But it’s good to see competition in the patch pump arena!