iLet Pump

I’m looking at different pump technologies (lots of new stuff out or shipping soon). The iLet pump is very intriguing and wondering if anyone has used this pump. My nutritionist saw it at a trade show recently, has no samples on hand, and is slated to get trained on it next month. However, am hearing they are working to ramp manufacturing and shipments. I’m interested in learning about user experiences while using this pump while doing varying intensity exercises. And in particular what you did before those different workouts (carb intake and pump disconnect/connect variables). And of course the results.

Am also interested in learning about sleep results while using this pump.

Whatever pump you choose, your doctor might make some recommendations on how to adjust for exercise (before, during and after) but you will likely change your strategy as you learn how your body reacts. For instance, some people’s numbers drop, whatever type of exercise they do; others find they rise with cardio but not other types.
Keeping detailed records will help you find patterns.
Looking forward to hearing what people have to say once they are on the new pump!

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@gmershon, I too have questions like yours as to how the iLet will perform under exercise, sleep, and also entirely skipping by meals and shifting meal hours. In other words, when living a normal - non-scheduled - human life.

The operating algorithm appears to be so different from the MiniMed and Omnipod basal intensive theory and the t-Slim more relaxed CIQ which I use. The iLet appears to be considerably less dependent upon I:C ratios and basal rates.

My t-Slim is midway through the fifth year - out of manufacturer warranty - and the iLet is on my short list for new purchase; I’m now waiting to hear results of real-life users.


@Dennis, agree with your missing meals. I’d like to understand that as well. I found some good comparison details about the new pumps at It has some info about iLet, but somewhat a summary about their online manual.

There are orders placed for this pump by other patients of my Dr’s and the Dr office will be going through training about it on 8/8 for supporting those patients. Let me know if you have other questions and I can request they find answers to them.

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Agree with that. Will be interesting as am thinking Dr’s will be learning from their patients given this is an entirely new and different pump.

I started on Omnipod5 about this time last year. I’m not sure I was my doctor’s only Omnipod patient but I was the first to use that particular device. Someone has to be number one! In the meantime my trainer was very helpful.

I read the iLet manual.

It doesn’t sound all that much different than the Tandem pump. You have to tell it when you eat a meal, whether it is breakfast, lunch or dinner, and whether it is a normal meal, or smaller or larger than usual.

It sounds to me like it starts with preset carb estimates for the meals and adjusts over time based on whether the meals you actually eat are larger or smaller than its presets, in the same way that Tandem’s Control IQ adjusts the amounts of insulin it gives you when your glucose gets high or low.

So, it sounds like a bit more automation than Control IQ but at the expense of less control at the beginning before the pump adjusts to you. After that, the results, as compared to Tandem, will depend on how good iLet’s algorithms are compared to Tandem’s.

The downside is that iLet uses a much smaller insulin cartridge (1.6 ml), which means more frequent changes.

Absent real world data that the iLet is giving users better glucose control, I would not be inclined to switch from Tandem. Otherwise it is just a question of whether the ILet or I have a better estimate of how many gms of carbohydrates I am actually going to consume at a particular meal.

The real breakthrough will be when we get faster acting insulin (either by change in the type of insulin or by change in the mode of injection) so that the pump gets a faster indication of whether glucose is going up or down and by how much, so that it can act faster. There can’t be faster correction of any low or high estimate of how much insulin will be needed, so long it takes 1.5 to 4 hours for the insulin to take effect. Our non-diabetic pancreases can act much faster and thus maintain tighter control because they inject the insulin directly into the blood stream, rather than into adipose tissue, as do our pumps and needle injections.

I just want to mention we asked our son’s endocrinologist about the new iLet pump and she told us she thought it was going to be more for type 2 diabetics.

I just hope over to the website and it is for Type1 adults and children 6 and up…
The fact that it does not use pre-set basal rates is similar to Omnipod5 auto mode, but other programming features go even further. Sounds like the next step towards a true artificial pancreas!

Interesting…this makes me wonder if maybe it’s the insurance companies who are wanting it prescribed for type two diabetics since the smaller insulin cartridge would mean more frequent site changes for those with type one.

Good point - I do wonder why they make it so small. Of course people’s total daily needs vary but I wonder if they are trying to force people to change every 3 days? Although it’s not recommended, some people may keep it on for 7, or until the cartridge empties out (that’s what I used to do).

John @schnauzer1, you have provided a very good summary and opened us to better understanding, and to questions about iLet; I too have read the User Manual and have spoken with a mechanic at Beta who currently uses the iLet.

A significant difference between the t-Slim CIQ and the iLet [also the 780G] is that correction bolus with CIQ is limited to no more than one per hour and delivers only 60% of calculated value; iLet and 780G deliver correction bolus doses as frequently as every five minutes. I suppose that the iLet may be better choice for people who chronically forget to bolus for foods eaten, but, IMO, the same people who struggle with carb-counting will continue to miss gauge “usual”, “larger”, “smaller”. I’ll continue counting carbs which I’ve been doing since the 1970s when on the “team” developing what is now referred to as MDI.

The first insulin pump with a 3 ml cartridge as “standard” was Tandem which came into existence 35 years into pump history; the three MiniMed pumps I used held 1.8 ml reservoirs, although considerable larger “pregnant” MiniMed pumps of each modal were available for 3 ml reservoirs.

My t-Slim has been out-of-warranty since mid-January and I currently have four [automated] systems under consideration. For me at my age, safety is a leading point; iLet has one unproven factor, MiniMed 780G has two unproven, OmniPod 5 zero unproven and T-Slim zero unproven. The “risk” of hypoglycemia from so many possible mini-bolus to possibly improve my management doesn’t appear safe. I began using CIQ the month it became available and since then, with my counted 230 carb-grams per day my TIR has exceeded 90% and HbA1c lab tests ranged between 503 and 5.7.

Have you tried either of the two FDA Approved Ultra Rapid Acting formulations? I’m not aware that any pump manufacturer has yet approved use in a pump. An endocrinologist gave me some for experimentation and asked me to give her a report; I don’t believe the Ultra helped me. The real breakthrough under testing is the “real” Beta Bionics two hormone pump, but even with this we won’t be close to an artificial pancreas. The pancreas produces 6 hormones - not just one or two.

John @schnauzer1, I was incorrect above.

FDA has cleared the use of FIASP [an ultra-rapid analog] prefilled cartridges in the iLet.

I suppose that FIASP and Lyumjev will soon be cleared for use in other systems.

Joanne , @WarriorMom13 the “smaller” cartridges / reservoirs used in insulin infusion pump are relatively new, and arrived with Tandem which came on the “pump scene” 35+ years after the first pumps.

Beginning around 1980, Lilly began marketing prefilled 1.6 or 1.8 [I don’t recall which] cartridges of fast-acting insulin which I used in my pens. The first Rapid-Acting, Humalog, didn’t exist until April 1996.

The .first three pumps which I used, all MiniMed marketed by Medtronic, used as standard 1.8 ml reservoirs. For heavy insulin users, a larger version “pregnant” pump with protrusion for 3 ml reservoir was available.

Or put another way Dorie, I wonder why Tandem caters to the relative minority of people who use 100 units of insulin per day.

Even your OmniPod holds a maximum of 200 inits.

I believe that Fiasp and Lyumjev have been FDA cleared for use in pumps, but Tandem (and I believe Medtronic) have not tested those insulins in their pumps, and essentially say “use at your own risk.”

Both Fiasp and Lyumjev reportedly cause more site irritation than do Humalog and Novalog. That is more problematic with pumps since the cannula stays in one place for 2 to 3 days rather than for less than a minute as with a pen or syringe. About a year ago, I asked my endocrinologist about using Lyumjev. She was somewhat negative. I dropped the issue because Humalog works for me, and I doubt that Lyumjev would be enough of an improvement to warrant the risks of trouble.

John E. Hoffman

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I’m just in 1.5 years of my 4 year warranty period on the Tandem, so I won’t be getting a new pump for at least 2.5 years, UNLESS one of the pump manufacturers offers a very low cost tradeup plan and the plan is available to Kaiser members. However, with the newer pumps having upgradeable software, I suspect that we’ll see the manufacturers upgrading their software as competitors come out with more advanced software. The trick with the algorithms is to make them robust enough to control glucose levels without going overboard and causing lows. One key to their success is storing historical data and using that data to refine the glucose predictions. As we get faster processors and more storage in the pumps over the years, the pumps will be able to store and process more data, and more complex algorithms, which hopefully will yield better predictions.

Having to change cartridges and infusion sets every 2 to 3 days is time-consuming. I’d like to see pumps go to U-200 insulin, which would double the time between changes without increasing the volume of liquid that the pump needs to carry. The downside, of course, is that with twice as much insulin on board, one could possibly get in greater trouble in case of a pump malfunction.

With insulin pumps, as with other medical equipment, the costs of development, obtaining regulatory approval, and tech support, greatly exceed the cost of the equipment and supplies. That’s why the manufacturers can be so generous with providing “free” replacements when users encounter problems, even when it is the user’s fault. Now, with upgradeable pumps, I think we’ll see the manufacturers regarding the situation even more as the sale of a subscription rather than the sale of a product. So far as I am aware, neither Tandem nor Medtronic has charged for an upgrade to an in-warranty pump. It seems that both companies are content so long as they receive the cost of a pump every 4 years, and the cost of a 3 month allotment of supplies every 3 months. After that, within reason, they will provide whatever the user needs at no additional cost, with it be a replacement pump or replacement cartridges and infusion sets. I doubt, however, that they will go to a purely subscription basis to the pumps, because it would be politically impossible for the companies to reclaim out of warranty pumps from people who cannot afford to pay for a new one.


The first computer processors were room-sized, and the very first insulin pump was carried on your back. Now we can fit a computer in a backpack and our pumps in a pocket (soon a coin pocket for Tandem!). I’m thinking they may not have chosen that size reservoir for people who use that much, insulin, but because it fit the size of device that was necessary at the time. Just a theory.
Attached is a picture of one of the very first imagine pumps, for those who would enjoy a bit of visual history.


I don’t mean to call you out, @schnauzer1, but you moved me to pipe in on something.
Lots of people complain about the time it takes to fill a cartridge. When I used Tandem the process took me about 5 minutes including “prime time” to load the tubing. I did pre-fill a few cartridges but that didn’t take long. The process for my Omnipod takes a little more than 5 minutes, party of which includes securing it with a barrier, shield and Simpatch.
It time really so bad? There are always other things we could be doing, but we may spend as much or more on social media or channel surfing without complaint, while people spend hours in dialysis or receiving chemo. So maybe those minutes we spend feeding our devices are more of a blessing than an object of complaint.
Again, not calling you out, just trying to look at it a little differently.

@Dennis, i have questions about the unproven factors you mention when describing pumps. Can you explain why TSlim has zero and Medtronic has 2? What do yu mean?